This afternoon, after House Republicans voted to “disagree” with the Senate compromise extending the payroll tax cut, the brinksmanship took a sudden and dramatic turn. Obama made a surprise appearance before reporters and called out John Boehner in the most direct terms yet to stop the games and pass the Senate proposal. He said:

House Republicans say they don’t dispute the need for a payroll tax cut. What they are holding out for is to wring concessions from Democrats on issues that have nothing to do with the payroll tax cut — issues where the parties fundamentally disagree. A one year deal is not the issue...

The clock is ticking. Time is running out. And if the House Republicans refuse to vote for the Senate bill, or even allow it to come up for a vote, taxes will go up in 11 days.

I saw today that one of the House Republicans referred to what they’re doing as “high stakes poker.” He’s right about the stakes. But this is not poker....This is not a game for the average family who doesn’t have 1,000 bucks to lose. It’s not a game for somebody who’s out there looking for work right now, and might lose his house if unemployment insurance doesn’t come through. It’s not a game when the millions of Americans take a hit when the entire economy grows more slowly because these proposals aren’t extended...

I’m calling on the Speaker and the House Republican leadership to bring up the Senate bill for a vote. Give the American people the assurance they need in this holiday season.

If Obama is to be believed, there will be no more negotiations. No more discussions. No move to “conference.” Either the House GOP supports the Senate compromise, which passed with overwhelming bipartisan support, or taxes go up on 160 million Americans. As a Dem aide told me earlier today, if it’s absolutely necessary, Dems are willing to allow the payroll tax cut to expire, and hammer House Republicans until they come back and pass the Senate extension. Obama implicitly seconded that just now.

After Obama’s appearance, John Boehner held a quick news conference in which he pushed back, demanding that Obama call on Senate Dems to renegotiate a compromise with House Republicans. But it’s not clear how much leverage House Republicans have left at this point. House Republicans were unwilling to even hold a straight up or down vote on the Senate proposal, suggesting they may have been worried it might pass the House against the GOP leadership’s will. Boehner claimed that a two month extension is merely “kicking the can down the road.” But this is a can that the public would rather see kicked down the road than off of it — if it is not kicked down the road, taxes will go up on millions. And a full-year extension can be negotiated after a shorter-term one is achieved.

Indeed, even Senate Republican aides are privately questioning the wisdom and leverage of the House GOP position. Polls suggest that the payroll tax cut fight may be enabling Obama to rebound, strengthening his position among key demographics on core questions, such as who can be trusted to protect the middle class. Obama even has an advantage now over Republicans on the signature GOP issue of taxes. He seems persuaded that Republicans will ultimately have to cave.

No question, Dems could still end up retreating from their hard-edged posture and enter into talks with the House GOP. But there are signs that this time may be different. Obama’s appearance today suggests he has calculated that he has already won this fight. He’s decided that if the worst happens, and the tax cut expires, Republicans will shoulder the blame for it. And his appearance also seemed like a warning shot: At a time when Congress is suffering record low approval numbers, he’s the one with the big megaphone, and he will continue to use it in the days ahead.