WASHINGTON — Opponents and supporters alike of comprehensive immigration reform have a message for anyone who thinks this week's shift in momentum means legislation is a done deal: don't get cocky.
Advocates of reform have had a great week: on Tuesday, Sen. Rand Paul endorsed an eventual pathway to citizenship for the 11 million undocumented workers in the United States. On Wednesday, Rep. Raul Labrador — who just a month ago dismissed a pathway as a poison pill — also came out in favor of it.
Pressure for a comprehensive package has gotten so intense, Senate Majority Leader Harry Reid even announced he'd bring legislation to the floor after the Easter recess.
And with bipartisan groups in the House and Senate continuing to make progress, supporters are starting to see the light at the end of the tunnel.
"I think the more you hear voices from all points say we have a possibility, that's a great sign," said Rep. Xavier Becerra, one of the leaders of a bipartisan group of House lawmakers working on legislation.
But Becerra, like most lawmakers involved in the effort, is cognizant of the fact that the movement toward reform could collapse at any time. "I think all of us who really believe there's a chance of getting something would really rather not comment other than to say that we're having good conversations" until legislation is ready, Becerra said.
Opponents were even more blunt in their warning.
"Some of the people who are talking about this haven't been through an immigration debate. In fact, a lot of the people lining up behind that leadership haven't been through an immigration debate. Those of us who were here in this congress in 2006 and 7 remember what that was like," said Rep. Steve King. "We remember the tens of thousands of people pouring into the Capital grounds on both sides of the issue, remember the phones being jammed" by constituent calls, the Iowa Republican explained.
"So I think there's going to be a constituent backlash against this thing soon, as they see it moving in that direction," King warned, adding, "Whether they can pass something before the American public wakes up, I don't know."
Conservatives may be increasingly comfortable with the idea of a pathway to citizenship — or, as Paul calls it, "probation" — but they're still very skittish when it comes to the kind of language used to describe it.
"It's an inaccurate phrase. It's inaccurate. There's a pathway to a green card, and then you can decide whether to apply for citizenship," said Sen. Marco Rubio, one of the Republican leaders of the Senate bipartisan reform effort.
"Everyone misunderstands how this process works. There's no such thing as a pathway to citizenship. You can't go from being an immigrant to a citizen, even today. You have to get a green card," Rubio said.
That squeamishness is understandable: as King noted, for movement conservatives "comprehensive immigration reform is amnesty" so even mentioning the word "pathway" can set off a bitter fight.
But even once lawmakers get beyond that linguistic hurdle — which is far from certain — there are still plenty of other traps that could kill reform, most notably how that pathway will work.
Will undocumented workers be forced to pay a fine? If so, how much? Everyone seems to agree that they will need to go to "the back of the line" to apply for green cards and eventually citizenship. But what does that mean, exactly? Will they have to live in the United States legally for some period of time before they can begin those processes, or will they be able to apply immediately?
Each of these questions, along with figuring out how to secure the border and reform the legal immigration system are all landmines that negotiators are still struggling to map out. Each one could easily derail the entire process.
"Any one of these things could undo all of this," a senior House GOP leadership aide said.
And then there's the problem of passing a bill in the House. While Labrador and a number of other House conservatives are moving toward the pro-reform camp, King is one of the leaders of a hardline group of conservatives that will simply not be swayed.
"Is [Rep.] Louie Gohmert going to do something? No. Is Steve King going to do something? No," the leadership aide said.
And while activists have speculated that Speaker John Boehner could use parliamentary tricks to pass the bill, aides said it is all but impossible for him to break the so-called "Hastert Rule," which requires a majority of Republicans to vote for a bill.
"Boehner can't break the Hastert rule on something as high profile as immigration. It wouldn't even be a question of him loosing his speakership. His entire leadership team would get thrown out," the aide warned.
Still, even opponents concede that the level of momentum is getting to the point where it could be difficult to block legislation.
"It's getting harder," King said. When asked if he was surprised, the conservative Republican said, "That it seems to have this level of momentum? Yes
… [They] seem to be reading the tea leaves of one part of the Republican Party without thinking for themselves. You wouldn't have this many people moving this far, this fast, if they were thinking for themselves."