He starts with 54 votes in the Senate, needing 60 and knowing that centrist Democrats don’t want to cross their own party on a bill that’s only going to end up being vetoed anyway.

Without those Democrats, the only leverage the GOP has is to refuse to fund Homeland Security until Obama agrees to scale back his executive action on immigration — however long that takes. That is to say, the “power of the purse” is really just a euphemism for the power to shut down the government, or part of the government. Senate Republicans have made it crystal clear that they refuse to exercise that power.

In which case, what’s left?

McConnell did not provide a path forward Thursday in the likely case that the House bill fails. Passing the House bill would “be our first choice,” McConnell said. “If we’re not able to do that, then we’ll let you know what’s next.”…

Senate Republican Conference Chairman John Thune declined to say Thursday whether the upper chamber would pass a clean funding bill for the department if the House legislation stalls in the Senate, but added: “We recognize the important role that the Department of Homeland Security plays in this country.”…

Sen. Rob Portman, R-Ohio, outlined the debate ahead of Thursday afternoon’s panel. “None of us want to see DHS face any kind of a shutdown threat. Too important,” he said. “But we also want to make sure we have done all we can to get the president to work with us rather than go around Congress and around the American people through his executive actions.”

If you won’t take Thune’s and Portman’s words for it, just listen to John Cornyn, McConnell’s top deputy in the Senate:

“The expectation by the rank and file in the House is it’s not going to come back even remotely similar to what we sent over there. And there is a real reticence by members of our conference to allow the funding to lapse,” [one House Republican] lawmaker added…

“No more drama associated with shutting down, for example, the Department of Homeland Security. That’s off the table,” Cornyn told reporters.

“Under no circumstances will we see any shutdowns,” he said.

And that’s that. Even if the bill passes the Senate, it’s a mortal lock that Obama will veto it. Now here’s the Senate majority whip all but telling you that if that happens, if O forces the GOP to decide between a DHS shutdown and a “clean” bill that funds Homeland Security with no concessions whatsoever on amnesty — a total capitulation by Republicans — they’ll choose the latter. All of this was entirely foreseeable when the GOP passed the “cromnibus,” setting up a showdown with the White House on DHS funding. McConnell and Cornyn have spent the two months since election day telling every reporter who’ll listen that job one for the new Senate majority is showing Americans it can govern. No more shutdowns, no more debt-ceiling standoffs. Message: It’s safe to elect a Republican president in 2016 and let the GOP control all of government. So what does the House do with the last major bill of the lame-duck session? They set up a shutdown-or-bust choice for the party on amnesty, an issue that’s laser-hot with their own base. Mystifying.

Let me repeat a prediction I made a few weeks ago, then: Precisely because the base is paying close attention, they won’t settle for a “clean” funding bill either. There’s a “security first” bill coming on immigration reform. The only question is when.

Leaders have tried to reassure colleagues worried about illegal immigration by pledging action on legislation to secure the border and strengthen enforcement policies against illegal residents. 

“Step 1 is to pass pretty much all of [Homeland Security Committee Chairman] Mike McCaul’s [R-Texas] border security bill. That’s the first step we’ll take,” said Rep. Kenny Marchant (R-Texas).

McConnell might get 60 votes for a security bill. Centrist Dems like Claire McCaskill fear a backlash from their party if they humiliate Obama by voting against amnesty, but security at the border and in the interior U.S. is a regular feature of the comprehensive immigration reform bills that Democrats routinely vote for. They won’t be crossing O by supporting it. They will be reducing their party’s leverage over comprehensive reform by supporting only the Republican-favored security half of it, but that matters less after Obama’s amnesty than it used to do. The legalization half of comprehensive reform has already been enacted: The GOP, by refusing to shut down DHS, will be effectively agreeing to legalization via executive order. That’s not a perfect deal for Democrats — a “security first” bill will have the force of statutory law whereas O’s legalization order could be undone by the next president — but everyone understands at this point, I think, that no successor from either party is going to undo O’s order. The politics are too tough. So yeah, McConnell might well get 60 for “security first.” The question is, would Obama sign a bill like that? And if he won’t, knowing that the GOP has essentially forfeited its power of the purse by forfeiting their power to shut down parts of the government, what leverage will they have to force him to sign?