President Bush and Democratic leaders of Congress failed to reconcile key differences Wednesday over a disputed war-funding bill that would set deadlines for the withdrawal of U.S. troops from Iraq.

Bush met with a bipartisan group of lawmakers in the Cabinet Room for more than an hour. Democrats said afterward they would send the president legislation soon that the White House says he will veto.

Senate Majority Leader Harry Reid said he still holds hope that Bush will sign the bill that lawmakers approve.

"We believe he must search his soul, his conscience and find out what is the right thing for the American people," Reid said, standing outside the White House. "I believe signing this bill will do that."

"It gives the troops more than he's asked for and leaves the troops there for considerable periods of time with some goals and benchmarks that have been called for by the American people, the Iraq Study Group and many, many military," Reid said.

Bush, who sat between House Speaker Nancy Pelosi and Reid, met with leaders of both parties as majority Democrats worked at drafting compromise legislation that provides war funding the president wants — but also is certain to include troop-withdrawal timelines that he has vowed to veto.

The sit-down came on the same day that four large bombs exploded in mostly Shiite areas of Baghdad on Wednesday, killing at least 178 people and wounding scores — the deadliest day in the city since the start of the U.S.-Iraqi campaign to pacify the capital two months ago.

Defense Secretary Robert Gates, traveling in the Mideast, called it "horrifying."

Bush invited the lawmakers to talk, but the chances for progress appeared bleak.

The White House said Bush would not negotiate. Republican lawmakers predicted Democrats will be forced to cave. Democratic leaders said they will not give ground in forcing a change in war policy, buoyed by public opinion running heavily against Bush's leadership.

The House-passed bill requires the withdrawal of combat troops by Sept. 1, 2008. The Senate measure is weaker, requiring the beginning of a withdrawal within 120 days, and setting a nonbinding goal of March 2008, for completion.

Both bills provide emergency funding for the wars in Iraq and Afghanistan.

Bush considers withdrawal timetables to be dangerous war policy that encourages enemies of the United States to wait for troops to leave. The president has also objected to billions in domestic spending that Democrats included in both bills.

The White House has sought to portray Democrats as indecisive, with each passing day coming at expense of the troops.

"One of the things that he's looking forward to hearing is how the Democrats have decided to compromise among themselves first so that he knows what their position is," Bush spokeswoman Dana Perino said just before the president met with lawmakers.

"They have several different positions, and as you can imagine, that's really difficult to negotiate with anybody if you don't know where someone stands," she said.

The administration took advantage of a recent congressional break to accuse Democrats of advocating a policy that would signal surrender in the global war on terror, and to demand they send Bush a bill he would sign.