The future of immigration reform is, for now at least, not up to House Speaker John Boehner. It is in the hands of a group of moderately conservative Republican senators who have to decide whether their desire to solve a decades-old problem outweighs their fears of retaliation from the party's right wing.

These senators are clearly looking for a way to vote for a bill that is the product of excruciating but largely amicable negotiations across partisan and ideological barriers. But these Republicans -- they include Bob Corker, John Hoeven, Susan Collins, Dean Heller, and Rob Portman -- want enough changes in the measure's border security provisions so they can tell tea party constituents that they didn't just go along with a middle-of-the-road consensus.

Here's their problem: Changes that so complicate a path to citizenship for illegal immigrants as to render it meaningless are (and should be) unacceptable to supporters of reform, including most Democrats. But if the GOP senators accept something short of this, they will face furious attacks from the hard-core opponents of any move toward large-scale naturalization of those who came here illegally.

In the end, there is no way around their dilemma. If they want a bill, they will have to take political risks.

Boehner got a lot of attention the other day for what appeared to be a firm statement that he would not let an immigration bill through the House without majority support from Republicans. On its face, his statement would seem to doom reform, given where that majority now seems to stand.

But as he typically (and, in his partial defense, perhaps necessarily) does, Boehner left himself wiggle room. "I have no intention of putting a bill on the floor that will violate the principles of our majority and divide our conference," he said.

Ah, yes, and let's remember that this week's "intention" does not necessarily determine tomorrow's strategy. It's in Boehner's interest to keep the large right end of his caucus at bay and to stake out a hard line to extract as many concessions from the Senate as he can. In the House at the moment, tomorrow is always another day.

What may matter is not how many Republican votes he gets but whether a majority of his caucus quietly decides that passing immigration reform is better for the party than blocking it. Many in such a majority might actually vote against a bill they privately want to see enacted. By doing so, they could satisfy their base voters back home while getting the immigration issue off the political agenda and ending the GOP's cold war with Latino voters.

This is not unduly cynical. Many essential laws have passed because legislators found a way to balance their political needs with their convictions. The movie Lincoln is instructive on the matter.

Such calculations explain the tensions among Senate Democrats over the best way forward. Politico recently reported on differences between Sen. Charles Schumer, the leading architect of the compromise bill, and Sens. Dick Durbin and Harry Reid, the majority leader.

Schumer is more willing to accept further compromises in order to get broad Republican support. He wants seventy votes for a bill, believing that a big margin would increase pressure on the House to act. He also wants to deprive Republicans of the chance to use procedural complaints as an excuse for voting no.

Durbin and Reid are wary of giving any more ground. They want to preserve negotiating space with the House and believe enough Republicans already know they have to support reform. They see the House as so unpredictable that watering down the bill may not, in any event, be very helpful.

Here's the potential positive news for immigration reformers: This difference may produce, if unintentionally, a good cop/bad cop dynamic that could keep the key group of Senate Republicans from undercutting the bill. Schumer can be open to a variety of border security changes, as long as they don't disrupt the path to citizenship. He can also be clear that there are limits on how far his party can go in providing the swing Republicans with political cover.

Which brings it all back to Corker and his allies. A Congressional Budget Office report on Tuesday showing that immigration reform could cut some $900 billion from the deficit over the next two decades should make it easier for them to make a deal. But in the end, they have to choose: Which side are they on?

(c) 2013, Washington Post Writers Group