U.S. lawmakers hammer Bush's new Iraq plan

Gates said extra troops would be sent in waves and that they might not all go if the Iraqi government did not keep its end of the bargain. Bush set no deadlines for the Iraqis in his White House address on Wednesday night.

Under the plan aimed at halting a collapse into civil war, Iraqi troops are to help sweep Baghdad neighborhoods clean of insurgents regardless of sectarian influences.

Early on Thursday, U.S. forces stormed an Iranian government representative's office in the northern Iraqi city of Arbil and arrested five employees, including diplomats and staff, Iranian officials said.

The U.S. military, without mentioning Iranians, said six people had been arrested in the operation, which came after Bush vowed to disrupt what he called the "flow of support" from Iran and Syria for insurgent attacks on U.S. forces in Iraq.

Democrats, in control of Congress after November elections seen largely as an anti-war referendum, spearheaded the challenge to Bush, who has failed previously to rally support for a conflict that has killed more than 3,000 Americans and tens of thousands of Iraqis.

But Arizona Republican Sen. John McCain, who had lobbied hard for a troop increase, said it was the right decision, though failure could unleash chaos in the region.

Senate Majority Leader Harry Reid said he expects to have the votes, with the support of some Republicans, to pass a non-binding resolution opposing the new deployment, which would bring American troop levels in Iraq to more than 150,000.

But leading Democrats stopped short of threatening to block funding for the new forces, mindful that would give Bush and his allies a chance to accuse them of abandoning the troops.

Taking his case to a largely receptive military audience, Bush called his plan the "best chance for success" in Iraq, but acknowledged it would not yield immediate results.

An ABC News-Washington Post poll showed he will have a harder sell with the American public, with 61 percent opposed to sending more troops and 36 percent supporting it.

Britain, America's chief ally in the war, said it would not send more troops to Iraq and still planned to reduce its presence in the south of the country, but supported Washington's plan to build up forces in Baghdad.

Anti-war activists were taking to the airwaves, the Internet and the streets to pressure Congress to deny funding. They said 1,000 protests were scheduled for Thursday night in all 50 states ahead of a January 27 march in Washington that organizers expect to draw hundreds of thousands.

(Additional reporting by Caren Bohan and Tabassum Zakaria at Fort Benning; and Steve Holland, Jeremy Pelofsky, Kristin Roberts and Andy Sullivan in Washington; Sophie Walker and Paul Majendie in London; and Ibon Villelabeitia in Baghdad)