Voters across the Northeast will head to the polls today in what amounts to the unofficial end to a wild primary season with the outcome of several ugly intraparty battles still very much in doubt.

Today’s primaries also give the national tea party movement its latest, and perhaps last, major opportunity to shape a local race that could help decide the balance of power in the new Congress. In Senate Republican primaries in Delaware and New Hampshire in particular, the establishment-backed candidates face aggressive challenges from tea party favorites.

Former Alaska Gov. Sarah Palin has waded into both races, as has Sen. Jim DeMint (R-S.C.). Fresh from an unexpected success in Alaska, the Tea Party Express has been on the ground in Delaware for the past week fighting against the wishes of the state and national GOP.

Finally, not to be lost among today’s flurry of electoral action, embattled Rep. Charlie Rangel (D-N.Y.) must survive a primary challenge from the son of a political rival under the most challenging circumstances of his 30-year political career.

Delaware

Among the seven states hosting primaries today, none has drawn more attention from the tea party movement than the First State.

The Republican Senate primary pits conservative pundit Christine O’Donnell against longtime Rep. Mike Castle, who until recently was considered the heavy favorite in the November matchup against Democratic New Castle County Executive Chris Coons for the seat long held by Vice President Joseph Biden.

But Castle might not get to face Coons.

With a boost from the tea party and national exposure to the race, O’Donnell is making life difficult for the more moderate Castle, who must survive a primary open only to registered Republicans.

Most Republicans believe O’Donnell is not a viable nominee because she would have little appeal to independents and Democrats in a general election.

Likewise, on the eve of today’s primary, National Democrats were nearly giddy at the prospect of an O’Donnell win and what it would mean for the overall playing field.

“The disarray in the Republican Senate primaries have given Democrats a competitive advantage in several key races,” Democratic Senatorial Campaign Committee National Press Secretary Deirdre Murphy said. “There are seven Republican establishment candidates who were unable to advance beyond their primaries and that has made the map much more favorable for Democrats.”

Revitalized by its successful fight for Joe Miller in Alaska, the Tea Party Express sent roughly 10 staffers to Delaware last week to drive get-out-the-vote efforts. Already the group has hosted several rallies and a radio-thon. Members waved signs in Newark and Dover on Monday morning and hosted phone banks for much of the evening in three cities.

Polling released Sunday night by the Democratic firm Public Policy Polling suggested that the race is a statistical tie.

O’Donnell led Castle 47 percent to 44 percent in the last poll before the primary.

Castle’s popularity took a dramatic hit in August as the race began to draw more attention, according to the survey results.

“The biggest winner of the Delaware GOP primary may end up being Chris Coons,” PPP President Dean Debnam wrote in the memo. “Running against O’Donnell or a wounded Castle will put him in his strongest position since he entered the race.”

In a similar PPP poll taken in August, Castle enjoyed a 60 percent favorability rating. But this weekend, just 43 percent of likely primary voters said they viewed the longtime Congressman favorably. The net negative rating can be attributed to 55 percent of voters’ belief that Castle is too liberal, the pollster explained in a memo.

Meanwhile, Castle’s Senate bid presents Democrats with one of their best opportunities to pick up a House seat this year.

Former Lt. Gov. John Carney has all but sealed the Democratic nomination for the at-large seat, while the GOP contest is in flux. National Republicans have been excited about the candidacy of Michele Rollins, a well-known lawyer who has the ability to at least partially self-fund the race. But the PPP poll results showed real estate developer Glen Urquhart with a 50 percent to 38 percent lead over Rollins.

Maryland

State Sen. Andy Harris’ road to the GOP nomination this cycle has been less eventful than two years ago, when he defeated former Rep. Wayne Gilchrest in a nasty intraparty battle.

This time, Harris has had the full support of the state and national party as he seeks a rematch with Rep. Frank Kratovil (D), who is considered one of the most vulnerable incumbents of the cycle. In today’s primary, Harris will have to defeat wealthy entrepreneur and Army veteran Rob Fisher (R), who has spent more than $550,000 of his own money on his campaign.

Fisher has tried to draw an insider vs. outsider contrast with the three-term state Senator.

“Certainly this race is a battle of two conservatives, but one of those conservatives happens to be a career politician and it doesn’t seem that that’s the best thing to be running on in this environment,” Fisher spokesman Demetrios Karoutsos said Monday.

Although Fisher launched a television ad campaign in August and has focused his late efforts on a direct-mail and robocall effort, his campaign hasn’t seemed to catch fire.

Harris has worked to ignore the relatively unknown challenger. In the final week of the primary, Harris was busy previewing his first general election commercial, which is set to air Wednesday.

Fisher earned a late primary endorsement from Gilchrest — who backed Kratovil in the 2008 general election and is expected to do so again in November — but it’s probably too little too late.

Massachusetts

The 10th district seat held by retiring Rep. Bill Delahunt (D) is the only competitive general election contest in the Bay State, a Democratic stronghold.

Republicans think they can flip this southeastern Massachusetts district, which now-Sen. Scott Brown won by 20 points in last year’s special election. Publicly, the Democratic Congressional Campaign Committee laughs off that possibility, although it has reserved TV time in the Boston media market to protect the seat.

Democrats think that Norfolk District Attorney Bill Keating has the edge in the Democratic primary against state Sen. Rob O’Leary. And Keating may have helped his cause when he won some earned media by chasing down a purse thief Sunday morning at a local restaurant.

The Republican primary has been ugly at times.

Former state Treasurer Joe Malone has repeatedly attacked state Rep. Jeff Perry, a former police sergeant, for a subordinate’s illegal strip searches of two teenage girls in the 1990s. And Malone has been bothered by news that more than $9 million was stolen by some of his aides during his stint as state treasurer.

Meanwhile, the 9th district offers an unlikely fight for Rep. Stephen Lynch (D).

Mac D’Alessandro won the endorsement of the Boston Globe in this suburban Boston district. And the Service Employees International Union has come out swinging for D’Alessandro, who previously served as the union’s New England political director.

The union has spent at least $250,000 to help D’Alessandro, according to filings with the Federal Election Commission.

The winner of the primary should cruise to victory in November. Neither the Republican nor independent challengers have raised more than $8,000 so far.

New Hampshire

The Republican Senate primary will lead most of the headlines, but primaries in each of the Granite State’s Congressional districts could be equally important in a state that the GOP hopes to sweep in November.

Much of the competition is focused on the GOP.

For the seat occupied by the retiring Sen. Judd Gregg (R), former state Attorney General Kelly Ayotte has long been considered the frontrunner in a four-way Republican contest that has drawn its share of national attention from conservative pundits. Former Alaska Gov. Sarah Palin (R) backed Ayotte in mid-July, and despite a rash of negative responses from local conservatives, Palin went to bat for Ayotte again in recent days, recording a robocall that describes Ayotte as a “Granite Grizzly.”

“Kelly’s opponents have been falsely attacking her for weeks. And the Democrat is afraid to run against her,” Palin said in the message.

The Senate contest turned negative in recent weeks as wealthy businessman Bill Binnie, who has loaned his campaign nearly $6 million so far, and Ayotte swapped attacks that centered on the former attorney general’s alleged mishandling of various cases. Binnie also questioned Ayotte’s credentials on abortion because of a legal settlement that she approved with Planned Parenthood.

Ayotte won the endorsements, however, of the Susan B. Anthony List and the National Right to Life Association.

The beneficiary of the infighting between Binnie and Ayotte has been businessman Ovide Lamontagne, a local tea party favorite who won DeMint’s endorsement over the weekend and enjoys substantial momentum going into today, according to another PPP survey released Sunday.

Ayotte led with 37 percent to Lamontagne’s 30 percent among likely Republican primary voters. Binnie garnered just 13 percent, while another conservative favorite, Jim Bender, finished with 12 percent.

“It looks like Kelly Ayotte will hang on, but the momentum has certainly been in Ovide Lamontagne’s direction so an upset is not out of the question,” PPP President Dean Debnam said.

The winner of the GOP race will face Rep. Paul Hodes in November. Ayotte, if she wins today, would be considered the early favorite in that matchup.

New Hampshire’s two Congressional seats — both currently held by Democrats ­­— are in play this November.

There is a crowded field of Republicans vying to oppose Rep. Carol Shea-Porter (D) in the 1st district. The field includes Manchester Mayor Frank Guinta, defense contractor Rich Ashooh and former Republican National Committeeman Sean Mahoney.

Things are a little more interesting in the 2nd district, the seat being vacated by Hodes.

Former Congressional candidate Katrina Swett is battling attorney Ann McLane Kuster on the Democratic side in a contest that has been relatively expensive and nasty at times. On the Republican ballot, former Rep. Charlie Bass is largely expected to beat the more conservative Jennifer Horn, although a low turnout could benefit Horn, who has more appeal to the party’s base.

New York

Few primaries have been bloodier this cycle than in New York’s 1st district, where a clash among four Republicans has drawn the interest of competing national pundits and rampant accusations of carpetbagging.

Many national Republicans initially stood behind businessman Randy Altschuler in the eastern end of Long Island, but some later rallied behind Chris Cox, a business consultant who happens to be the grandson of President Richard Nixon. Former Securities and Exchange Commission attorney George Demos complicated things last week when he drew the endorsement of Rush Limbaugh.

Limbaugh blasted Cox for being a “pro-choice, country-club blue blood.” And all of the candidates have accused each other of not living in the district.

The infighting is likely to leave the eventual nominee pretty bruised for the November contest against Rep. Tim Bishop.

Also not helpful for Republicans is the fact that it’s possible that one of the candidates who fails to win the primary could appear on the November ballot as a member of the Conservative Party. That would likely split the Republican vote, all but ensuring Bishop keeps his seat.

Sound familiar?

That’s the same scenario that played out in New York’s upstate 23rd district last fall, where Rep. Bill Owens took a seat that had belonged to the GOP since the 19th century.

There are indications that it could happen again.

Conservative candidate Doug Hoffman won the backing of the tea party last fall, but the Republican base ultimately split, giving Owens the victory. Hoffman is back again, this time against fellow Republican businessman Matt Doheny in the GOP primary.

Today’s contest could again divide the Republican and Conservative tickets in the 23rd district, giving Owens’ re-election prospects a boost this fall.

Of course, it’s impossible to preview New York’s primaries without looking at the 15th district race that features the 20-term Rep. Charlie Rangel.

The 80-year-old Congressman has repeatedly dismissed pressure from Washington Democrats and primary opponents to retire, despite swirling ethics charges that Republicans hope to use to pull down the entire party. A New York Times poll last week found that 70 percent of Manhattan voters think Rangel should resign or drop out of the race.

Still, he has shown no sign of doing so. New York City Mayor Michael Bloomberg (I) recently taped a robocall backing him. And many political observers believe Rangel will win today’s contest. Should he do so, he is all but assured to win the general election in his heavily Democratic district.

Rangel’s chief opponent is state Assemblyman Adam Clayton Powell IV, son of the man Rangel unseated in 1970. If ever there was a year for an upset, this is it.

Also worth mentioning are New York’s 13th and 14th districts.

Rep. Michael McMahon (D) has no primary challenger in the 13th, a swath of Staten Island and Brooklyn that Sen. John McCain (R-Ariz.) won in 2008. But Republicans Michael Grimm, a former FBI agent, and environmental policy expert Michael Allegretti are fighting for the opportunity to flip the seat in November. Both have been active fundraisers so far, and either could be competitive in the general election.

In the 14th district, Rep. Carolyn Maloney (D) faces a tough primary against Reshma Saujani, a hedge fund attorney and political fundraiser. Each had spent more than $1.1 million as of Aug. 25.

Rhode Island

Four credible candidates are vying in the Democratic primary to replace retiring Rep. Patrick Kennedy (D) in this heavily Democratic district.

Civility reigned initially, but the race turned increasingly nasty in recent weeks, which is just what Republicans need to happen for this seat to be competitive in November.

Republican state Rep. John Loughlin — running against a token challenger today — has largely been silent as Democratic hopeful and political newcomer Anthony Gemma teed off against perceived frontrunner Providence Mayor David Cicilline.

A recent statewide Gemma radio spot highlights the capital city’s high unemployment rates, empty buildings, failing infrastructure and foreclosures.

Political observers believe the attacks were likely too late to help Gemma but could hurt Cicilline in the general election, should he survive today’s open primary.

Wisconsin

While most of the contests are centered in the Northeast, there is one exception.

Republican Ron Johnson seems likely to coast past nominal challengers in the Senate GOP primary, and the wealthy businessman will face Sen. Russ Feingold (D) in the general election.

The state’s most competitive House primary is in the race to oppose Rep. Steve Kagen (D). Three Republicans have the potential to win the primary. Reid Ribble is considered the nominal favorite and is already part of the National Republican Congressional Committee’s Young Guns program, having been named to its lowest tier in October. Another contender, state Rep. Roger Roth, is the nephew of former Rep. Toby Roth, who represented this district from 1979 to 1997. Former state Rep. Terri McCormick, who lost the GOP primary in 2006, also has a shot at the nomination, but most observers see it as a race between Ribble and Roth.

Wisconsin’s Government Accountability Board estimated in early September that turnout would set a record, beating the record of 27.9 percent in 1964. The open gubernatorial race and open races in the state Legislature are driving turnout.

John McArdle and Tricia Miller contributed to this report.