WASHINGTON — A sharply divided House voted Friday to order President Bush to bring combat troops home from Iraq next year, a victory for Democrats in an epic war-powers struggle and Congress' boldest challenge yet to the administration's policy.

Just over an hour later, an angry Bush accused Democrats of staging nothing more than political theater and said that if the spending bill is not approved and signed into law by April 15, troops and their families "will face significant disruptions."

Ignoring Bush's promised veto, lawmakers voted 218-212, mostly along party lines, for a binding war spending bill requiring that combat operations cease before September 2008, or earlier if the Iraqi government does not meet certain requirements. Democrats said it was time to heed the mandate of their election sweep last November, which gave them control of Congress.

"The American people have lost faith in the president's conduct of this war," said House Speaker Nancy Pelosi, D-Calif. "The American people see the reality of the war, the president does not."

Joined at the White House by veterans and service family members, Bush said: "A narrow majority in the House of Representatives abdicated its responsibility by passing a war spending bill that has no chance of becoming law and brings us no closer to getting the troops the resources they need to do their job.

"These Democrats believe that the longer they can delay funding for our troops, the more likely they are to force me to accept restrictions on our commanders, an artificial timetable for withdrawal and their pet spending projects. This is not going to happen."

The House vote, echoing clashes between lawmakers and the White House over the Vietnam War four decades ago, pushed the Democrat-led Congress a step closer to a constitutional collision with the wartime commander in chief. Bush has insisted that lawmakers allow more time for his strategy of sending nearly 30,000 additional troops to Iraq to work.

The roll call also marked a triumph for Pelosi, who labored in recent days to bring together a Democratic caucus deeply divided over the war. Some of the party's more liberal members voted against the bill because they said it would not end the war immediately, while more conservative Democrats said they were reluctant to take away flexibility from generals in the field.

Republicans were almost completely unified in their fight against the bill, which they said was tantamount to admitting failure in Iraq.

"The stakes in Iraq are too high and the sacrifices made by our military personnel and their families too great to be content with anything but success," said Republican Whip Roy Blunt, R-Mo.