To the very limited extent that congressional Democrats have enjoyed the last four years of gridlock on Capitol Hill, they have derived pleasure from watching the Republican Party rupture over and over again, its divisions between the conservative Tea Party and the establishment leadership preventing just about any real legislative accomplishments.

As afternoon turned to evening on Thursday, it was the Democrats who were turning on each other. House Minority Leader Nancy Pelosi and Senator Elizabeth Warren, the liberal darling, railed against a White House-backed spending deal that narrowly passed the House just a couple hours before a midnight deadline for keeping the government open. During a marathon, closed-door meeting in the Capitol basement, Democrats debated two key questions: whether a pair of giveaways for Wall Street and wealthy donors in a $1 trillion bill were cause for shutting down the government, and whether they could get a better deal from Republicans by rejecting this one.

"It does not get better," Representative Gerry Connolly, a Virginia Democrat who voted for the bill, said on Friday morning. "There were a number of us that respectfully had a different point of view that we didn’t have the kind of leverage that Elizabeth Warren was suggesting." He was referring to the spending package, but he could have been talking about his party's prospects as a whole in 2015. Come January, Republicans will run not just the House but also the Senate, and the debates among Democrats about exactly how far they should retreat will become familiar. In lobbying for the bill, which passed the Senate on Saturday night, the White House highlighted increased funding to fight Ebola and for regulatory agencies like the FCC, but officials focused just as much on what the Republicans didn't gut, namely Obamacare, the president's climate plan, and his immigration policy. That, too, will become the norm.

Tempers peaked after the administration formally endorsed the legislation Thursday afternoon, just as Democratic opposition was building. Taking to the House floor, Pelosi assailed Obama's support for the bill and said Democrats had been "blackmailed." Despite her denunciation, Pelosi's office insisted she was not lobbying her members against the proposal. So, was she trying to torpedo the bill, or did she merely want to send a message to Republicans and the president that Democrats couldn't be taken for granted? "I did not get the impression that Leader Pelosi was simply trying to make a point," Connolly said. "I got the strong impression that she was urging the caucus to vote down the bill."

The bill's passage angered Pelosi's allies, who were disappointed that the party did not rally behind her. "It was a missed opportunity to reinforce the contrast between Republicans and Democrats," Representative Steve Israel, a member of the Democratic leadership, said by phone Friday morning.

Indeed, for Democratic critics of the proposal, the two offending provisions—a rolling back of regulations on the trading of derivatives by banks and a significant loosening of restrictions on political contributions by the wealthy—struck at the core of the populist, middle-class message the party needs to hold the White House and win back Congress in 2016 and beyond. "If you're not showing the public you're willing to fight on these issues," Representative John Sarbanes of Maryland asked, "what are you willing to fight for?"

The when-to-fight-and-when-to-fold arguments were reminiscent of those that have buffeted the GOP in recent years, in which Speaker John Boehner and Senator Mitch McConnell have struggled to contain Tea Party lawmakers demanding to fight Obama at every turn. By late Thursday, the objections of Warren and the liberal wing had all but drowned out the conservative protests from Ted Cruz and his allies in House, who opposed the spending bill as too conciliatory to the president. Unlike a year ago, the blame for a government shutdown this time would have gone to liberal Democrats, not the Tea Party.

The three-hour caucus meeting Thursday evening became a venting session for Democrats who were still looking to make sense of their electoral drubbing a month ago. In an interview, Sarbanes argued that the party needed a moment to recapture the public's attention—a "soundcheck on the mic," he said—and this was as good as any. His side may have lost the vote, but he said the battle gave Democrats a chance "to clarify a message to a very disaffected public that we can build around."

For a while on Thursday, it looked like liberals would actually succeed in sinking the appropriations bill. Led by Pelosi and Warren, opponents had seized the momentum and forced Republicans to delay a vote for hours. Obama dispatched Denis McDonough, the White House chief of staff, to speak to Democrats, but he didn't change many minds. According to one person in the room, it was only when Steny Hoyer of Maryland, the minority whip and chief deputy (and occasional rival) to Pelosi, stood up at the end of the meeting to say he would support the bill that the tide turned. Opponents were stunned. "No, Steny, no," cried Maxine Waters, the veteran California liberal. A senior Democratic aide said the White House had been building support throughout the day, but Hoyer's backing gave additional cover to undecided Democrats, and ultimately 57 of them joined with Republicans to put the bill over the top shortly after 9:30 p.m.

Pelosi tried to put a positive spin on the episode, writing in a letter to her colleagues on Friday that Democrats had succeeded in maintaining leverage to the end and that the lengthy meeting had produced "a unity of purpose and a clarity of message." Yet for the leader and her allies, the defeat offered a hard lesson that is now familiar to Republicans: Before you can rally the country, you have to unite your party.

"The White House and House and Senate Democrats will have to be playing on the same field," Israel said. Heading into 2015 and the new Republican Congress, that might prove the biggest challenge of all.