Now that Super Duper Tuesday has come and gone, the 2010 Senate landscape is all but set.

Except for a pair of competitive primaries in New Hampshire and Colorado and a runoff in North Carolina, we know who most of the players will be and where the battles will take place in the fight for control of the Senate this cycle.

Ten or 11 Democratic seats are in play this fall, compared with just five or six for the GOP. That means Senate Republicans would need close to a clean sweep to gain a 51-seat majority. While that still appears to be a tall order, the GOP clearly has the opportunity to make significant gains in the Senate.

North Dakota and Delaware seem to be almost certain pickups for Republicans, and it’s hard to see how Democrats will be able to defend everything in a vast battleground that includes Illinois, Indiana, Arkansas, Colorado, Nevada, Pennsylvania and Washington and once-safe seats in California and Connecticut.

However, Republicans can’t spend all their time and effort on offense because they have several open seats that will require attention and resources in Florida, Kentucky, Missouri, New Hampshire and Ohio. National Republicans will also have to make sure that Louisiana and North Carolina don’t slip into more competitive categories.

Interestingly, neither Republicans nor Democrats are entering the general election with the team that they set out to recruit at the beginning of the cycle.

It seems like so long ago that Democrats failed to entice Delaware Attorney General Beau Biden or North Carolina Rep. Bob Etheridge into making the leap to a Senate race. More recently, Democrats saw their favorite party switcher, Sen. Arlen Specter, fall in spectacular fashion in Pennsylvania’s primary last month.

The GOP field of candidates has undergone even more upheaval since the start of the cycle. Along with letting Rep. Dean Heller slip the recruiting hook, national Republicans witnessed the implosion of Florida Gov. Charlie Crist’s Republican bid, the rise of former Florida Speaker Marco Rubio, the unexpected excitement for Rand Paul in Kentucky and Sharron Angle in Nevada, and the candidacy of former World Wrestling Entertainment CEO Linda McMahon in Connecticut.

But despite a national environment that appears certain to continue to favor Republicans this fall, Democratic Senatorial Campaign Committee Chairman Bob Menendez (N.J.) said he is optimistic coming out of Tuesday’s elections.

“Today is certainly a very good day for us,” he said. “A very strong incumbent won her election, and some of the worst Republican candidates won their elections.”

Menendez said Sen. Blanche Lincoln did more than simply run against Washington, D.C., in her Democratic runoff victory over Lt. Gov. Bill Halter. She demonstrated that she was “a true independent voice” for Arkansas and that, he said, will pay dividends in the general election.

Arkansas political consultant Bill Paschall agreed that Lincoln will likely employ the same formula that she used against Halter in the race against Rep. John Boozman (R).

“They were trying to create the sense and image that Blanche was beholden to no one but the people of Arkansas,” Paschall said. “Lincoln will continue some of the strategy she used with Halter and try to tie Boozman to special interests and try to make him the special interest candidate.”

Republicans scoff at the idea that Lincoln could have been in any way strengthened by her grueling primary.

To begin with, the intraparty fight drained her multimillion-dollar campaign war chest, one of her big advantages entering the cycle. But more importantly, Lincoln’s battle against Halter forced her to move to the left as she fought for her political life. That effort culminated with Lincoln dropping ads that touted the fact that she became a key vote to pass the controversial health care reform bill in the Senate. That’s an issue Republicans are certain won’t play well in the general election this fall.

One national Republican consultant asked: “What has really changed for the Democrats in the past 48 hours?”

The consultant pointed out that Republicans now have candidates that they can unite behind in battleground states such as Nevada and California, while Democrats are left with incumbents like Lincoln and Majority Leader Harry Reid (Nev.), who are consistently polling behind their challengers.

National Republican Senatorial Committee Chairman John Cornyn (Texas) said Democrats and the Obama administration “have seriously underestimated the mood and the energy of the voters.”

“Considering Blanche Lincoln trails John Boozman by 20 points, [California Sen.] Barbara Boxer is facing the toughest fight of her career, and Harry Reid is still losing to Sharron Angle despite spending $10 million already, I shudder to imagine what the Democrats would consider a bad day,” NRSC spokesman Brian Walsh added.

But Menendez said Angle’s nomination gives Nevada Democrats a big reason to be optimistic.

“Nevada is the latest state where Republicans chose an extremist” as their general election nominee, he said, adding that there was a reason why establishment Republicans rallied around former state party Chairwoman Sue Lowden in Nevada and Secretary of State Trey Grayson in Kentucky.

Democrats have already hit Angle for wanting to phase out Social Security and Medicare, eliminate the Department of Education and allow nuclear waste to be stored at Yucca Mountain.

While Republicans would like nothing better than to make the entire Nevada Senate campaign a referendum on Reid — whose approval ratings have been consistently poor this cycle despite his campaign having spent about $7 million already — Menendez said his job will be to draw the contrasts with GOP candidates.

“I have said all along that our races, in any part of the country, and that includes Nevada, is a race of contrasts and to give voters a choice,” he said.