With Republicans looking to regain control of the Senate and Democrats hoping to pad their majority in 2008, neither party appears inclined to make the political sacrifices necessary to pass a broad immigration bill this year and may be content to simply duel to a rhetorical draw this summer, lawmakers and strategists in both parties said.

Leaders from both parties, Judiciary Chairman Patrick Leahy (D-Vt.) and Sen. Edward Kennedy (D-Mass.) have all vowed to pass reform legislation this year, and Kennedy has been meeting with the White House and presidential hopeful Sen. John McCain (R-Ariz.) in recent weeks to work out a new compromise bill.

But despite these efforts, it still appears unlikely that comprehensive reforms will move out of the chamber before electoral concerns kill the bill.

In fact, GOP and Democratic aides contend that both parties may be best served by a political impasse over the issue, since such a scenario would allow Members to show they are standing firm on the hot-button issue while avoiding compromises that may upset base voters.

“Really, a filibuster is a win for us,” one Democratic aide said, arguing that it would fit into the broader message to voters that Republicans are blockading reforms.

Similarly, a GOP aide argued that “blocking a bill is good for us” since Republican incumbents would be able to avoid facing the ire of single-issue conservative base voters come Election Day.

Despite massive protests across the nation and the rise of conservative vigilante groups along the Mexican border, Congress was unable to pass broad immigration legislation last year, in large part because of deep divisions within the Republican Party over the scope of the reforms.

While President Bush and some rank-and-file Republicans sided with most Democrats and backed a broad reform bill that included allowances for some illegal immigrants to remain in the United States, the bulk of the GOP opposed such a broad measure. Instead, most Republicans in the House and Senate favored a much narrower approach that focused on border-control measures, more aggressive enforcement of current immigration laws and a new system for ensuring employers do not hire undocumented workers.

Those differences apparently have widened since the elections. Although the Senate successfully passed a comprehensive immigration bill last year with the backing of a number of Republicans, it is unlikely such a bill will garner as much support from the GOP this year. A number of lawmakers — including Senate Minority Leader Mitch McConnell (R-Ky.) — voted for last year’s bill because they knew the GOP-controlled House would act as a last barrier against enactment of any form of amnesty for illegal workers.

But with Leahy and Kennedy both backing provisions that are significantly more pro-immigration than those that were included in last year’s bill, Majority Leader Harry Reid (D-Nev.) and the White House may find it difficult to muster as much support in the Senate now that the backstop of a GOP-controlled House no longer exists.

“Anything with even a hint of amnesty” will have to face stiff opposition, one Republican Senator said, adding that “the gulf is just so wide” between Republicans in Congress and the White House that Bush may find little traction in the chamber.

Indeed, a number of lawmakers already are chafing at the fact that the White House, Kennedy and McCain have been holding closed-door meetings on a bill.

GOP Sens. Sam Brownback (Kan.) and Arlen Specter (Pa.) — the former chairman of the Senate Judiciary Committee and a supporter of the comprehensive plan last year — complained last week that they had been frozen out of the process of drafting this year’s bill.

As a result, Brownback said he would team up with other Republicans, including Specter and Sens. Mel Martinez (Fla.) and Jon Kyl (Ariz.), to work on the issue and perhaps introduce their own bill.

Last year, Kyl led a team of Senators that opposed the comprehensive bill supported by Specter, Brownback and Martinez.

Brownback explained the strategy of partnering with Kyl, saying in an interview, “If we can get a bill that all of us can agree to and hold 40 votes together, then we can have a real debate on the issue. Like last year, you still need 60 votes.” Sixty votes would be needed overcome a filibuster.

Democrats, meanwhile, face their own political difficulties. Given Reid’s narrow majority in the Senate, Democrats will find it all but impossible to pass a bill that goes as far as many in the party’s left wing will want. Additionally, one Democratic leadership aide pointed out that passing a wide-ranging reform package over the protests of Republicans could end up motivating the GOP’s base to turn out in next year’s election, making it difficult for Democrats to widen Reid’s margin of control in the 111th Congress.

This aide also pointed out that many Democrats elected to the House in 2006 ran, in part, to the right of Republican incumbents on the immigration issue and that passing comprehensive reforms that allow millions of illegal immigrants to remain in the U.S. could make their re-election much more difficult.

An added pressure facing both parties will be the timing of any immigration fight. Like Social Security reform, immigration has become something of a “third-rail” political issue, making it all but impossible for Congress to address it during an election year.

Although supporters have indicated they would like to take up the issue this spring — possibly as soon as the week after the annual Easter recess — leadership aides in both parties predict that the debate won’t begin until August at the earliest. That timeline would butt the debate up against the annual appropriations fight, meaning Congress will have a very narrow window in which to pass bills in both chambers, conference the legislation and get it to Bush before it becomes politically unviable.

Nevertheless, Kennedy, who is spearheading efforts to pass immigration reform this year, is pressing ahead. Kennedy is using this week to publicize his efforts, holding a series of public events with the Irish Lobby for Immigration Reform, religious leaders and other immigration reform advocates.

According to Kennedy’s office, this year’s version of the legislation will contain the main elements of last year’s Senate legislation. “The basic concepts are intact,” said Laura Capps, a Kennedy spokeswoman.

Those elements, she said, include a path to citizenship for illegal immigrants in the U.S. who meet several requirements, including working in the country for several years, paying a penalty, paying back taxes, and learning English and civics. They also would have to “get at the back of the line” behind immigrants already seeking citizenship, she added.

The bill also will call for enhanced border security, tighter requirements for employers to verify worker eligibility and a system to allow workers to enter legally into the U.S. to satisfy labor needs.

Beth Crowley of CongressNow contributed to this report.