When I wrote How a Trump Emergency Declaration Became the Mother of All Headaches, I explained how the Senate Republicans stumbled into the situation they now face where they’re on the brink of losing a vote in a chamber they control.  Senate Majority Whip John Cornyn of Texas is already resigned to defeat, “I didn’t want it to come to this, because I think it’s probably going to get tied up in court. And I said it wasn’t a practical solution…All it takes is four right? You can do the math as well as I can.”

When Sen. Cornyn says, “It only takes four,” he means that if four Senate Republicans vote for a resolution overturning Trump’s emergency declaration then it will pass, assuming all the Democrats and the two independent also vote ‘yes.’ There are already three GOP senators on the record with an intention to approve the measure: Susan Collins of Maine, Lisa Murkowski of Alaska, and Thom Tillis of North Carolina.

Sen. Tillis went so far as to write an opinion piece for the Washington Post explaining his decision. Here’s the key part of his argument:

Conservatives rightfully cried foul when President Barack Obama used executive action to completely bypass Congress and unilaterally provide deferred action to undocumented adults who had knowingly violated the nation’s immigration laws. Some prominent Republicans went so far as to proclaim that Obama was acting more like an “emperor” or “king” than a president.

There is no intellectual honesty in now turning around and arguing that there’s an imaginary asterisk attached to executive overreach — that it’s acceptable for my party but not thy party.

Republicans need to realize that this will lead inevitably to regret when a Democrat once again controls the White House, cites the precedent set by Trump, and declares his or her own national emergency to advance a policy that couldn’t gain congressional approval.

Because the declaration of disapproval will pass the Democratically-controlled House of Representatives on Tuesday and is a privileged resolution authorized by the National Emergencies Act, the Senate is compelled to bring it up for a vote within fifteen days.

There is a flaw in the law, though, because the president is allowed to veto Congress’s disapproval.  No one is yet predicting that there will be enough Republican defections in either the House or Senate to sustain a veto override attempt.  As a result, the main tangible effect of Congress passing the resolution will be to add heft to judicial challenges to the emergency declaration.

Nonetheless, the debate is roiling Republican unity in Congress. Opposition is widespread, but the appetite for taking Trump on is weak.

Numerous Senate Republicans say that, like Tillis, they despise Trump’s decision to declare a national emergency to get additional funding for his wall. But most aren’t ready to say they will vote to block him from doing so.

Interviews on Monday with more than a dozen GOP senators who have been publicly critical of Trump’s unilateral maneuver or warned him not to deploy it were cagey about their intentions for what would be a crucial vote in coming weeks on the Senate floor…

…Some Republicans still privately expect the resolution to pass the Senate, but there was little enthusiasm to get out in front of a conflict with the president.

As I wrote previously, the Republicans welcomed this emergency declaration because it gave them a way to avoid overriding a presidential veto so that they could reopen the government. But that only delayed their day of reckoning. What they’re going to do now is the absolute worst of all worlds. First they’re going to rebuke the president and then they’re going to fail to override his veto and hand him control of their pursestrings. They won’t avoid one of the toughest votes they’ll ever face, and they won’t defend their own power and prerogatives. They won’t stand with Trump, but they’ll still defer to him. And then they’ll hope that the courts side with them against Trump, thereby defeating Trump’s efforts to build a wall on the border with Mexico with American tax dollars.

They deserve this fate, but they also deserve the contempt they will get from every single quarter for their cowardice and lack of principle.