To much fanfare, a bipartisan group of eight Senators on Monday announced they had agreed on a blueprint for overhauling the nation’s immigration laws. Despite the optimistic tone to the news conference, Monday is likely to be the best day of the year for proponents of comprehensive immigration reform.

It’s relatively easy to agree on broad outlines balancing border security and employer enforcement with a pathway to citizenship for illegal immigrants. The difficult part is what comes next — putting everything into detailed legislation, grappling with the logistics and trying to win a critical mass of votes. The more legislation moves toward border security and employer enforcement to attract Republicans, for instance, the more it would alienate Democrats. President Obama opposes making border enforcement a precondition to allowing a path to citizenship. And Sen. Marco Rubio emphatically told Hot Air’s Ed Morrissey, “I will not be supporting any law that does not ensure that the enforcement things happen.” This is just one of many policy gaps that will be hard to bridge.

One of the lesson’s we’ve learned from divided government over the past several years is that nothing at all gets done unless it absolutely has to. That’s been the case with the deals that have been struck to avert government shutdowns, raise the debt ceiling and avoid the “fiscal cliff.” But America’s immigration system falls into the category of problems — like entitlements — that should be addressed, but won’t be because there’s no date certain that they must be.

Whether or not lawmakers are earnest about wanting to resolve the issue, politically, all sides could live with doing nothing. Democrats would still be able to use it as a wedge issue and Obama could argue he really tried on immigration this time, but Republicans were simply intransigent. Conservative House members could go back to their districts and say they successfully blocked amnesty. Republicans like Rubio could argue that they really wanted immigration reform to happen, but Obama was simply unwilling to compromise to get it across the finish line. As long as all sides have fall back positions in the event that nothing gets passed, it’s hard to see how this survives the legislative meat grinder.