President Trump has issued countless threats to shut down the government unless Congress approved money for the border wall. But Republicans in Congress are about to ignore him one more time by adding another two weeks to the shutdown clock. They’ll have until Dec. 21 to resolve differences and pass the final set of spending bills that were delayed on Oct. 1. After nearly two years in office, it’s now perfectly clear that this Congress won’t fund the wall and the next one — with the House led by Democrats — is even less inclined to do so. Trump’s chances at pushing through a signature campaign proposal have never been slimmer, a result of presidential weakness and internal conflicts among congressional Republicans.

A big question remains unanswered: How would Donald Trump even force a government shutdown anyway?

Well, there are actually three ways. The simplest one would just be if he vetoed a spending bill that didn’t include wall funding. But that one won’t work. A funding bill won’t reach Trump’s desk unless it clears both chambers of Congress, which means it needs the backing of the majority Republican leadership (or else it wouldn’t get a vote). And such a bill — one without wall funding — would lose some Republican votes, so it will need a lot of Democratic votes to pass. In other words, it would be a compromise both parties in Congress could live with and pass by large, veto-proof margins in both chambers. Trump could veto it, but Congress would override.

The second way looks even easier for Trump, but wouldn’t work out well at all for him and Republicans. The House could try to pass a bill with wall funding and blame Democrats when it fails. But Republicans alone probably wouldn’t have the votes to pass it, since many conservatives would only back a budget that deeply cuts spending elsewhere. Republicans, once again, would need votes from Democrats, and most Democrats won’t vote for the wall.

The only way this potentially works for Republicans, then, is the third option: Find the votes to get a bill through the House that funds the wall without slashing spending, and then hope for a Democratic filibuster in the Senate. They can then blame Democrats for shutting down the government. But that one only works if they can get a bill out of the House that can get to a Senate majority; otherwise, the bill simply fails, there’s no filibuster blocking things, and Republicans are obviously responsible. For now, there are still only 51 Republicans, so they need all but one to stay on board if Democrats band together. And it’s not at all clear that all 51 Republicans would be willing to vote for funding a border wall under any circumstances, much less that they’re willing to engage in a government shutdown fight over it.

In fact, what’s much more likely is that most House and Senate Republicans have no interest in taking on this battle at all right now. After all, voters just rejected their party after an election in which the president’s closing argument centered on the border. And Trump’s clout with Congress is at an all-time low. Even if the leadership wanted the confrontation, Trump wouldn’t be able to help assemble a winning coalition.

The two-week delay makes that obvious. As budget expert Stan Collender wrote, Republicans would push the spending bill through if they had the votes right now. If Republicans do choose to shut down the government on Dec. 21, Democrats will only have to wait 13 days until the new Congress convenes and they move into the House majority. Even if public opinion turns against the Democrats, which seems highly unlikely given that the wall is unpopular, the party surely could remain unified enough to drag things out that long and reap the increased leverage they would have beginning on Jan. 3. Especially since Democrats would be in the position of supporting any additional temporary measure to keep the government open while negotiations continued.

In other words, if they want to try to use a shutdown to force Democrats to go along with funding Trump’s wall, every day they wait makes their position a little weaker. I have no idea whether Trump realizes that or not, but two other GOP leaders most certainly do: Majority Leader Mitch McConnell and outgoing Speaker Paul Ryan.

So what appears to be happening now is that McConnell and Ryan are just ignoring Trump’s bluster, and moving ahead with the compromises they need to make to get out of town and finish off the necessary business of the expiring Congress. And Trump has had about the same success convincing a Republican-majority Congress to pay for his wall as he did getting Mexico to do it.

Jonathan Bernstein is a Bloomberg Opinion columnist covering politics and policy.