AMERICA’S first government shutdown in more than four years looks likely to end only three days after it began. Over the weekend of January 20th and 21st, the two parties seemed to be digging in. But by 1pm on Monday, January 22nd the Senate voted 81-18 to end the shutdown and back a bill to fund the government until February 8th. Paul Ryan, the House speaker, said his caucus would pass the bill quickly. Government shutdowns are costly and embarrassing; on the Senate floor during the vote there were a lot of smiles. They may not be there long. For now the worst has been averted, but the disagreement that precipitated the shutdown is starker than ever.

And now it has an added layer of procedural uncertainty. In exchange for voting to reopen the government, Democrats wrung a promise from Mitch McConnell, the Senate majority leader, to bring a legislative fix for DACA (Deferred Action for Childhood Arrivals)—an Obama-era executive action that shielded hundreds of thousands of undocumented immigrants brought to America as children from deportation—up for a vote.

But, as Claire McCaskill, a Democratic senator from Missouri, said in the bowels of the Capitol after the vote, “We’ve watched Mitch McConnell make promises that never materialised.” The Senate Republican leader secured Jeff Flake’s vote for the tax-reform bill late last year by promising a legislative solution to DACA. He won Susan Collins’s vote by promising to advance two health-care bills she believed would mitigate the harm of repealing the Affordable Care Act’s mandate that people buy insurance. He has so far kept neither promise.

The difference this time, said Tom Udall, a Democratic senator from New Mexico, was that he made his promise not just to a single senator, but to a group of 14 centrists that helped hammer out the compromise. “When a leader promises 14 senators he’s going to do something,” said Mr Udall soon after the vote, “you have to do it.”

Not everyone was so sanguine. Ezra Levin, who heads Indivisible, a liberal pressure group, called the deal “morally reprehensible and political malpractice.” Among the 18 no votes was almost every Democrat thought to have presidential aspirations in 2020—including Cory Booker, Kirsten Gillibrand, Kamala Harris, Chris Murphy, Bernie Sanders and Elizabeth Warren—as well as a few others, such as Dianne Feinstein, worried about a primary challenge. Ms Harris said she feared putting “the lives of nearly 700,000 young people in the hands of someone who has repeatedly gone back on his word.” But Mr McConnell’s promise was not open-ended; if he reneges and fails to bring a DACA bill up for a vote by February 8th, Democrats can shut down the government again.

Any bill that gets through the Senate still has to pass the House and be signed by Donald Trump. That is more difficult than it sounds. Just five days ago Mr McConnell said publicly that he had no idea what Mr Trump wanted or would sign. Mr Trump himself may not know. Initially he urged Congress to pass a bipartisan “bill of love” to let DACA recipients stay. Everyone knows what the contours of such a bill will look like: a path to legal residency, if not citizenship, for DACA recipients in exchange for beefed-up funding for border security and, probably, stronger internal enforcement of immigration laws. But when Charles Schumer, the Senate minority leader, proposed just such a bill, Mr Trump rejected it. “Negotiating with President Trump,” Mr Schumer said, “is like negotiating with Jell-O.”

That Jell-O may be hardening quickly. During the brief shutdown, Mr Trump’s campaign released an ad snarling that “Democrats who stand in our way will be complicit in every murder committed by illegal immigrants.” Kirstjen Nielsen, the homeland-security secretary, tweeted, “Benefits for millions of illegal immigrants instead of paying Americans who put their lives at risk daily to protect ours? I don’t think so.” Those statements are gross, lurid distortions that collapse the distinction between DACA recipients and murderers, and imply that a DACA fix somehow gives recipients “benefits”—rather than sparing America the cost of deporting them while ensuring that they pay federal income tax. They show the influence of Mr Trump’s most hardline supporters, such as Stephen Miller and Tom Cotton, who want not just a more secure border, but less immigration overall, both legal and illegal. Mr Udall believes that “the president does not want to govern on this issue” and has “no hope that he’ll sign a DACA bill even if it passes”. That does not bode well for the next three weeks’ negotiations.