It’s inevitable that immigration “negotiations” in Congress will deadlock and Trump will end up declaring an emergency on the 15th, if not sooner, to save face and try to get the wall built. We’ve been chattering for weeks about the court battle that would follow that but we should start paying attention to the congressional battle that will follow it too. POTUS is likely to find himself in a position similar to the one he found himself in the day before the shutdown ended, when Schumer’s bill to reopen the government got more votes in a Republican Senate than Trump’s compromise offer on immigration did. Namely, a critical mass of his own party in the Senate will turn against him.

Is he prepared to fight a legal and PR battle on his emergency authority to fund the wall if the GOP-controlled Senate votes to disapprove of that authority? We’ll know soon. A Friday leftover from WaPo:

Senate Majority Leader Mitch McConnell cautioned President Trump privately this week about the consequences of declaring a national emergency to build his border wall, telling him the move could trigger political blowback and divide the GOP, according to two Republicans with knowledge of the exchange…

That would take place under provisions of the National Emergencies Act, which provides that a presidential declaration can be terminated if lawmakers pass a joint resolution to do so. House Democrats would be likely to move swiftly to approve such a resolution, and the law provides that it would come to the Senate floor, where it would require only a majority vote to pass.

At least a half-dozen Republican senators are fiercely opposed to the idea of an emergency declaration, generating enough opposition that a disapproval resolution could pass the Senate with the support of the 47 Democrats and a handful of GOP senators — the scenario about which McConnell warned Trump.

In any other situation the GOP’s play here would be clear. Pelosi’s Democrats would pass a resolution of disapproval and McConnell would stick it in his pocket and forget about it, just like he did with the various House bills to reopen the government during the shutdown. David Drucker reports that that’s not an option in this case, though. The Congressional Review Act essentially compels a floor vote in the Senate when there’s a joint resolution aimed at overturning a new regulation. Senate Republicans will be forced to go on the record and choose between angering Trumpists by voting to block Trump’s grab for wall funding and angering virtually everyone else by voting to let him proceed. Here’s what they’re up against:

A poll from Monmouth last week found a similar split, 34/64. A third poll from Morning Consult was more forgiving but still had a majority opposed at 38/51. A vote on Trump’s emergency decree is a loser for McConnell and Republicans facing reelection in 2020 — maybe a double loser insofar as most of the caucus will vote with POTUS to stay on the good side of Trump voters but enough will split off and join Democrats to ensure passage anyway. (Note the detail in the excerpt above about how there’s no filibuster in this case.) That means Trump fans will be treated to headlines like “REPUBLICANS BOLT, JOIN DEMS TO REBUKE TRUMP EMERGENCY ON WALL” even if most Republicans stick with the president. Populists will be pissed off.

But it gets worse. Even if a joint resolution passes, it needs to be signed into law by the president to take effect. Trump will veto it, of course, meaning that the Senate Republicans who voted to block him on the first vote will have nothing to show for their efforts and the entire caucus will now be forced to take a second vote on whether to override POTUS’s veto. (I assume they’ll be forced. I’m not sure if McConnell can table a veto-override attempt after the joint resolution has passed.) This friction between him and McConnell’s caucus will play out for days or weeks. Even in the best-case scenario for border hawks, where the Senate fails to muster 67 votes to override his veto — which is all but assured, as GOP senators wouldn’t dare block his chance at building the wall — Democrats will be able to rightly say that a bipartisan majority of both chambers of Congress opposes an emergency decree.

That’s not the end, though. I wonder how Congress’s wrangling over the emergency decree might affect the eventual court battle. If Senate Republicans did somehow revert to their 2014 selves and override Trump’s veto on grounds that the executive shouldn’t be able to commandeer appropriations when Congress hasn’t approved them, the White House would probably challenge it on separation-of-powers grounds. Ann Coulter’s been pushing that approach, in fact — supposedly Trump has inherent authority under Article II as commander-in-chief to take Pentagon money and apply it as he sees fit towards national security. If on the other hand the veto override fails and Trump is sued by Democrats over his emergency decree, the fact that a joint resolution of disapproval passed Congress might be germane to the Supreme Court’s analysis. The most famous case on executive authority and congressional approval is the Youngstown Sheet & Tube case from 1952, and the most influential opinion from that case was Robert Jackson’s concurrence. Jackson argued that the president acts with maximum constitutional legitimacy when he has some form of approval from Congress and minimum legitimacy when Congress disapproves. Passage of a joint resolution disapproving of Trump’s emergency decree would be about as strong as evidence can get that Congress views Trump’s actions as illegitimate.

Would that be enough for the Court to strike down his emergency decree or would they be inclined to punt on this, deeming it a “political question” that American voters can resolve next year? If they do strike it down, it would mean that not just a Republican Senate but a Republican Supreme Court acted to thwart Trump on his signature immigration process. I’m sure that’ll go down fine with populists who elected him to seal the border and appoint judges who’d let him do so.