As immigration reform takes center stage in the nation's capital, the thorny issue of creating a pathway to citizenship for millions of illegal immigrants is once again emerging as a potential deal-breaker for both sides in this heated debate.
What they agree on is simple: The nation's immigration system is broken. What they don't agree on is almost everything else.
Sen. Lindsey Graham, R-S.C., one of the key negotiators in the so-called Gang of 8 which is drafting a bill, remained confident Monday.
"It's long overdue," Graham said on Fox News. "If we don't do it now, it will be a decade or more before anyone takes it up again."
But Graham's comments for compromise come at a time when many conservatives remain opposed to a fundamental plank -- creating a pathway to citizenship for the 11 million illegal immigrants estimated to be living in the U.S. Despite a recently announced and highly touted agreement between business and labor on a separate guest-worker program, conservatives remain uncomfortable with the idea of rewarding someone for breaking the law of the land. Republican Sen. Ted Cruz, who despite his freshman status has become a strident voice for the conservative wing of the party, recently said that "insisting on a path to citizenship is the surest way to kill the bill."
Yet Sen. Rand Paul, R-Ky., another important voice in the new guard of the GOP, last month endorsed the idea of letting illegal immigrants get in line and eventually apply for citizenship.
In the past, only a handful of Democrats have put their weight behind a legalization plan that didn't include a path to citizenship. Now, almost all say a proposed plan must have a way for illegal immigrants to one day become citizens. New York Democratic Sen. Charles Schumer has been vocal in his support and says the path to citizenship is not something they will compromise on and that giving illegal immigrants the ability to "right a wrong" is crucial.
As it stands, the Gang of 8's working plan is said create a 13-year pathway to citizenship for illegal immigrants currently in the country. It also would provide a new class of worker visas for low-skilled immigrants and crack down on employers hiring undocumented workers.
On the pathway debate, lawmakers fall all across the spectrum. While some outright oppose it and others insist on it, a critical contingent is working on finding a middle ground. Key details will include what fines and requirements those applying for citizenship would have to abide by. And, perhaps more politically critical than anything, is the issue of border security -- Republicans who are willing to get behind the pathway proposal insist that border security be measurably improved first.
Lawmakers have repeatedly asked the Obama administration for guidelines to judge if border security has been beefed up and whether initiatives are in place and are working -- but have had little luck in getting a straight answer. In late March, senior Homeland Security official Mark Borkowski told Congress the department had not completed any new measurements and was not going to be able to do so in coming months. The news seemed to surprise both Republicans and Democrats.
"We need to assure the American people that we have effective control of the border and we have made advances to achieve that," Arizona Republican Sen. John McCain said. "I need to have something to assure people they are not going to live in fear."
Some Democrats say that demands for improved measures and metrics is a tactic being used by conservatives to edge out millions of immigrants on the path to citizenship. Not being able to adequately determine security at the borders could be a deal breaker for some lawmakers.
"We do not want the Department of Homeland Security to be the stumbling block to comprehensive immigration reform for this country," said Rep. Candice Miller, R-Mich.
Miller, who is the chairwoman of the House Homeland Security subcommittee on border security, told Borkowski at the hearing that the lack of a security measure "could be a component of failure to pass something I think is very important for our country."
Obama and other Democrats are wary that demands for measured progress on border security could effectively stall anybody on the pathway.
"Regardless of how much additional effort we put in on the borders, we don't want to make this earned pathway to citizenship in which it's put off -- further and further -- into the future," Obama said last week. "There needs to be a certain path for how people can get legal in this country, even as we also work on these strong border security issues."
Not every issue involving immigration reform is stuck in negotiations.
Late last week, the U.S. Chamber of Commerce and the AFL-CIO, the largest labor federation, reached an agreement on a guest-worker program.
"With the agreement between business and labor, every major policy issue has been resolved," Schumer, a member of the Senate Gang of 8, said on NBC's "Meet the Press."
While Schumer's enthusiasm may have been a bit premature, the debate is moving forward and the bill could reach the Senate floor as early as next month.
Over the in the House, it's a different story. Unlike the bipartisan group of senators expected to unveil a legislative proposal soon, the House probably won't take up the topic until June. A small group of House Democrats and Republicans is meeting privately to develop their own set of principles similar to the Senate's Gang of 8.
In recent months, Republicans have voiced concern that perceived hostility toward illegal immigrants is driving away a growing electorate and setting them up for future problems at the polls.
Hoping to change that dynamic is Republican star and possible 2016 presidential contender Sen. Marco Rubio of Florida.
Rubio, a member of the Gang of 8, has been involved in softening the conservative stance on the issue. He's made it clear that he supports a path to citizenship. However, in a letter last month to Senate Judiciary Committee Chairman Patrick Leahy, D-Vt., Rubio reiterated that border security "and other enforcement triggers" must be met before illegal immigrants can apply for permanent residence.