WASHINGTON —The Democratic-led Congress and the White House are headed back to square one after President Bush yesterday vetoed a war spending bill that he called “a prescription for chaos and confusion.”

Mr. Bush fulfilled his promise to reject legislation that ties needed funding for the Iraq war to a timetable for the withdrawal of American troops.

“The bill would mandate a rigid and artificial deadline for American troops to begin withdrawing from Iraq,” the president said in a televised White House address shortly after 6 p.m. He issued the veto, the second of his presidency, within a few hours of congressional leaders delivering the $124 billion emergency spending bill to the White House.

Mr. Bush noted that the legislation requires commanders to begin redeploying soldiers in as soon as two months and no later than October 1.

“It makes no sense to tell the enemy when you plan to start withdrawing,” Mr. Bush said, restating an argument he has been making for weeks. “All the terrorists would have to do is mark their calendars and gather their strength and begin plotting how to overthrow the government and take control of the country of Iraq.”

Minutes later, Democratic leaders responded. “If the president thinks that by vetoing this bill he’ll stop us from working to change the direction of this war in Iraq, he is mistaken,” the Senate majority leader, Harry Reid, said.

The House speaker, Rep. Nancy Pelosi, said Mr. Bush “misrepresented” the bill; she said it “honored and respected the wishes of the American people.”

“The president wants a blank check,” Ms. Pelosi said. “The Congress is not going to give it to him.”

The Democrats do not have the votes to override Mr. Bush’s veto, and they have appeared divided on exactly how to proceed. Fervent anti-war lawmakers have urged the leadership to stand its ground and push legislation that would mandate withdrawal. Others, including Senator Clinton, have said that route is unrealistic without greater Republican support. Mrs. Clinton last week suggested that Democrats would not want to risk being blamed if troops in battle do not get the funding they need.

Mr. Bush and congressional leaders from both parties are set to meet at the White House today. Each side indicated a desire to resolve the impasse, but neither indicated much willingness to compromise.

“We look forward to working with the president to find common ground, but there is great distance between us right now,” Ms. Pelosi said last night.

Adding drama to yesterday’s showdown, the Democrats sought to highlight the fact that it coincided with the fourth anniversary of Mr. Bush’s speech aboard the U.S.S. Abraham Lincoln, in which he appeared under a banner that read “Mission Accomplished” and declared an end to major combat operations in Iraq. The image has become perhaps the most infamous of his presidency.

The leading Democratic presidential candidates all issued statements marking the occasion and rebuking Mr. Bush. Mrs. Clinton called it “one of the most shameful episodes in American history.”

The White House denounced attempts by Democrats to link the funding bill to the anniversary of the president’s speech. “It is a trumped-up political stunt that is the height of cynicism,” a spokeswoman, Dana Perino, said, “and it’s very disturbing to think that they possibly held up this money for the troops and the troops’ families and the resources they need to try some p.r. stunt on this day.”

In a briefing with reporters aboard Air Force One, she declined to comment on whether the president would consider softer benchmarks for the Iraqi government in a new spending bill, according to the White House transcript.