The Democratic plan approved in the House on Friday, which provides $100 billion for military operations but calls for almost all American combat troops to leave Iraq in 2008, was instantly greeted with a Presidential veto threat. A similar plan is advancing in the Senate, but under the same threat. Moreover, it is not at all clear that House Democratic leaders can continue to hold their ideologically sprawling caucus together on future Iraq votes.

But whatever the flaws of the plan approved Friday, it is a Democratic plan—and one that won with a strikingly — some would say shockingly — unified vote from House Democrats. Republicans did not make it easy; only two voted for the measure. But Democrats produced the other 216 votes from their own ranks, mindful, in the end, that this was simply a must-win — for Speaker Nancy Pelosi and for the party as a whole.

Ms. Pelosi and her leadership team worked hard to woo the conservative Democrats who felt the legislation went too far, as well as the liberal Democrats who felt it did not go far enough. They held caucuses, private meetings, conversations on the House floor — and pieced together a majority, a vote at a time, while fighting the longstanding divisions that critics loved to highlight as “Democrats in disarray.”

Critics quickly noted that the majority on this vote could be a fleeting thing. “You’ve got to ask yourself, why go through this long, drawn-out exercise of going and wheeling and cajoling and trying to buy votes within your own party when, in fact, you know it’s not going to go anywhere,” said Tony Snow, the White House spokesman.

Mr. Snow noted, in essence, that Democrats would have to quickly go back to the legislative drawing board, given the President’s resistance to their plan, and given the fact that, “the need for funding the troops is urgent, the clock is running.”

But the vote did several things for the Democrats. It was a sharp rebuke to the President, a clear message that “his policy of more troops, more money and more time has overstayed its welcome,” as Representative Rahm Emanuel, the Democratic caucus chairman, put it after the vote. It established their initial stance in the legislative bargaining that will follow. And it helped them at least begin to deliver on the campaign promise so many made last year, to wind down the war.

“The American people expect us to do something,” as Representative Steny Hoyer, the majority leader, put it in Friday’s debate.

Ms. Pelosi and her team also proved something that could have major implications for 2008 - that they could manage, even harness, the tensions between the party’s left and the party’s establishment.

There is a long history of anger and mistrust between the left and many of the Democratic leaders on Capitol Hill, dating back to 2002, when some of the most prominent Democrats voted to give Mr. Bush the authorization to use force in Iraq. Even now, with legislation establishing a timeline for withdrawal, many anti-war activists felt the party was not moving fast enough. But many, notably Moveon.org, still got on board and pushed for its passage.

Speaker Pelosi “has given enough indications to the Moveon crowd that she is trying to bring an end to this war in a way that’s possible, that she’s convinced them to join her incremental politics,” said Julian Zelizer, an expert on Congress at Boston University.

Many liberals in the House said that, in the end, they could not make the perfect the enemy of the good, an argument advanced by Representative Steve Cohen, a Memphis Democrat, in a caucus this week. He wanted to hold out for a better bill, he told his fellow Democrats, but realized, “That’s akin to what the Ralph Nader people felt in 2000, and that vote gave us George Bush.”

Still, Vin Weber, a former Republican House member, and currently a lobbyist and party strategist, said Democratic leaders face the prospect of disappointing their liberals in the future. “At some point they’re going to have to fund this war on terms acceptable to the President,” Mr. Weber said. “If I were Nancy, I’d take credit for getting the party united behind this. But it’s a very transitory victory for them.”