U.S. soldiers of the 1st Platoon, Alpha Company, 2nd Battalion, 12th Cavalry Regiment take position as they patrol a street in Baghdad's north-west Shi'ite neighborhood of Sholla March 20, 2007.[Reuters]

WASHINGTON - Democrats in the US Congress pressed on Thursday for a timetable for a US troop withdrawal from Iraq, ignoring White House threats of a presidential veto on any bill that ties nearly $100 billion in combat funds to a 2008 pullout.

The US House of Representatives began debate on legislation to bring all American combat troops out of Iraq by September 1, 2008. The measure cleared a procedural hurdle, and a close vote on passage is expected on Friday.

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With the Iraq war dragging into its fifth year and American casualties mounting, the debate in Congress took on bitter tones.

"I am getting a bit tired of those who were consistently wrong from the beginning on the issue of Iraq, lecturing those of us who were consistently right from the beginning in our opposition to this war," said House Appropriations Committee Chairman David Obey, a Wisconsin Democrat.

His Republican counterpart on the committee, Rep. Jerry Lewis of California, responded that Democrats "cannot have it both ways; pretending to support our troops, while undercutting the ability to prosecute their mission."

As the House debate began, the Senate Appropriations Committee approved a plan requiring President George W. Bush to begin pulling combat troops out of Iraq this year, with the goal of completing that withdrawal by March 31, 2008. The bill is expected to be considered by the full Senate next week.

Senate Republicans opposed to setting a withdrawal date let the bill pass the panel on a voice vote after realizing that the absence of one ill Democratic senator could produce a tie that would bottle up the bill -- which is needed to fund US combat operations in Iraq and Afghanistan -- in committee.

"When the bill is in the Senate, I intend to move to strike the (pullout) language," said Mississippi Republican Thad Cochran.

WHITE HOUSE WARNING

Anticipating the congressional debate, the White House issued another in a string of strong warnings.

"The one (bill) they are considering has zero chance of being enacted into law. It's bad legislation, the president's going to veto it and Congress will sustain that veto," White House spokesman Tony Snow said.

House Democratic leaders kept scrambling to nail down the 218 votes they need to pass the bill.

Rep. Maxine Waters, a California Democrat who wants an immediate end to the Iraq war and is expected to vote against her party's bill, said a group of fellow anti-war House Democrats now plan to support the controversial measure.

While she would not predict the outcome, Waters said, "It gives them (House leaders) a better chance to pass the bill."

House Republicans were expected to overwhelmingly oppose the legislation because of the troop withdrawal timetable and other conditions being placed on the funds. "This is just the opening round of several months of discussions," House Republican leader John Boehner of Ohio said, predicting that in the end Congress would provide the money without conditions.

Congress is trying to finish the emergency war-funding bill by next month, when the Pentagon says it will run out of money to keep about 140,000 troops in Iraq. But experts think the Defense Department could continue the war into May or June while Congress and Bush fight over the direction of the war.

Democrats want to provide Bush the money he has requested, and more, to continue fighting in Iraq this year and to strengthen US forces in Afghanistan. But given sagging public support for the Iraq war and the 2006 elections that were seen as a repudiation of Republicans' handling of it, Democrats are hard-pressed to give Bush the money without the conditions.

If they fail in this attempt to wind down the war, Democrats are expected to target other bills this year.

Sen. Daniel Inouye, a Hawaii Democrat, said it was not worth continuing to spend US lives and money in Iraq.

"At the end how many of us can truly still believe that we will emerge victorious with a Jeffersonian democracy on the Tigris banks" asked Inouye, who lost an arm in World War Two.