The Capitol dome is seen on Capitol Hill in Washington, Tuesday, Dec. 11, 2012. (J. Scott Applewhite/AP)

A key group of senators from both parties will unveil on Monday the framework of a broad overhaul of the nation’s immigration laws, including a pathway to citizenship for more than 11 million illegal immigrants.

The detailed, four-page statement of principles will carry the signatures of four Republicans and four Democrats, a bipartisan push that would have been unimaginable just months ago on one of the country’s most emotionally divisive issues.

The document is intended to provide guideposts that would allow legislation to be drafted by the end of March, including a potentially controversial “tough but fair” route to citizenship for those now living in the country illegally.

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It would allow undocumented immigrants with otherwise clean criminal records to quickly achieve probationary legal residency after paying a fine and back taxes.

But they could pursue full citizenship — giving them the right to vote and access to government benefits — only after new measures are in place to prevent a future influx of illegal immigrants.

Those would include additional border security, a new program to help employers verify the legal status of their employees and more-stringent checks to prevent immigrants from overstaying visas.

And those undocumented immigrants seeking citizenship would be required to go to the end of the waiting list to get a green card that would allow permanent residency and eventual citizenship, behind those who had already legally applied at the time of the law’s enactment.

The goal is to balance a fervent desire by advocates and many Democrats to allow illegal immigrants to emerge from society’s shadows without fear of deportation with a concern held by many Republicans that doing so would only encourage more illegal immigration.

“We will ensure that this is a successful permanent reform to our immigration system that will not need to be revisited,” the group asserts in its statement of principles.

The framework identifies two groups as deserving of special consideration for a separate and potentially speedier pathway to full citizenship: young people who were brought to the country illegally as minors and agricultural workers whose labor, often at subsistence wages, has long been critical to the nation’s food supply.

Expanding visas

The plan also addresses the need to expand available visas for high-tech workers and promises to make green cards available for those who pursue graduate education in certain fields in the United States.

“We must reduce backlogs in the family and employment visa categories so that future immigrants view our future legal immigration system as the exclusive means for entry into the United States,” the group will declare.

The new proposal marks the most substantive bipartisan step Congress has taken toward new immigration laws since a comprehensive reform bill failed on the floor of the Senate in 2007.

It comes as the White House is gearing up for a renewed push for reform. On Tuesday, President Obama will travel to Las Vegas to urge quick action; he told Hispanic members of Congress at a White House meeting Friday that the issue is his top legislative priority.

The emerging bipartisan consensus over immigration has developed with remarkable speed, as leading Republicans have concluded the GOP must quickly shift in response to its sweeping November election loss or risk becoming a permanent minority in a nation with a growing number of Latino voters.

Obama won roughly seven in 10 Hispanic voters last fall, exit poll data show, while Mitt Romney carried just over a quarter of the Latino vote, which had increased its share of the electorate.

Romney won an even smaller share of the Hispanic vote than did the party’s 2008 nominee, Sen. John McCain (R-Ariz.), stoking widespread post-election concerns among Republicans.

“I’ll give you a little straight talk,” said McCain, a member of the bipartisan working group, on ABC’s “This Week With George Stephanopoulos” on Sunday. “Look at the last election. Look at the last election. We are losing dramatically the Hispanic vote, which we think should be ours, for a variety of reasons, and we’ve got to understand that.”

The group’s Republicans also include Sen. Marco Rubio of Florida, Sen. Lindsey O. Graham of South Carolina and Sen. Jeff Flake of Arizona. Rubio unveiled a similar list of principles to guide reform three weeks ago that has received a surprisingly warm reception from leading conservative pundits.

Rubio has insisted that those who came to the country illegally must wait in line behind those who pursued legal routes, a view he reiterated in a Sunday op-ed in the Las Vegas Review-Journal.

Some immigration advocates fear that Rubio’s approach would result in waits that last for decades. But the group’s chances of bipartisan success were boosted with Rubio’s decision to sign on. A potential 2016 presidential contender, Rubio is particularly popular with tea party groups that have been opposed to immigration reform.

Although advocates have long assumed that legislative action would probably begin in the Democratic-held Senate, House Speaker John A. Boehner (R-Ohio) said last week that members are working on the issue on a bipartisan basis in his chamber as well. It is “time to deal” with immigration, he declared.

In addition to the political imperative for the GOP, McCain said Sunday, current immigration laws are simply unsustainable and must be changed. That analysis was echoed by Sen. Robert Menendez (D-N.J.).

“First of all, Americans support it, in poll after poll. Secondly, Latino voters expect it. Thirdly, Democrats want it. And fourth, Republicans need it,” Menendez said on “This Week,” explaining the rationale for quick action.

The framework is the result of intense behind-the-scenes talks between the senators, who have met five times since the November election, rotating between offices of McCain and Sen. Charles E. Schumer (D-N.Y.).

Other Democrats involved are Menendez, Sen. Richard J. Durbin (D-Ill.) and Sen. Michael F. Bennet (D-Colo.). On Sunday, Schumer informed top White House officials of the group’s progress and alerted them to the impending Monday announcement.

Key details to settle

Many details remain to be negotiated before legislation can be introduced. They include the especially difficult question of how the government would verify that enforcement has been sufficiently enhanced to allow an expanded pool of legal residents to seek citizenship.

“Our goal, once we get our principles, is to sit down and negotiate a bill. That is often difficult. How is the path to citizenship? How does it work?” Schumer told reporters in New York on Sunday. “We’ll have to work all that out.”

But, he added: “I’m impressed with my colleagues on both sides of the aisle over their desire to meet in the middle.”