WASHINGTON - US President Bush's troop-boosting plan for Iraq was headed straight into a political gale in Congress, with Democrats, some Republicans and an increasingly organized anti-war movement arrayed against the buildup.

Lawmakers were ready to pounce on the plan Thursday during a day of congressional hearings featuring top Bush administration officials such as Secretary of State Condoleezza Rice and Defense Secretary Robert Gates. Leaders of the Democratic-controlled Congress also were considering options for a nonbinding resolution, to be introduced next week, denouncing the troop increase.

Also Thursday, a coalition of labor, anti-war groups and liberal organizations planned to announce a multimillion-dollar advertising and grass-roots campaign against the commitment of extra troops.

While Congress assessed his plan, Bush was to visit Fort Benning, Ga., on Thursday in an effort to sell his new strategy to the public in the face of mounting opposition to the war. Polling by AP-Ipsos in December found that only 27 percent of Americans approved of Bush's handling of Iraq, his lowest rating yet.

In a 20-minute prime time speech Wednesday, Bush took responsibility for mistakes in Iraq and outlined a wide-ranging strategy to pull Iraq out of its spiral of violence. Its key feature inserts 21,500 more U.S. troops into Iraq, increasing the current presence from 132,000 to 153,500 at a cost of US$5.6 billion. The highest number was 160,000 a year ago in a troop buildup for Iraqi elections.

"If we increase our support at this crucial moment, and help the Iraqis break the current cycle of violence, we can hasten the day our troops begin coming home," Bush said.

Resisting calls for troop reductions, Bush said that "failure in Iraq would be a disaster for the United States."

Congressional Democrats and a handful of Republicans promptly criticized the plan as an ill-advised escalation that would further mire the United States in Iraq. Several noted that the president's strategy contradicted the advice of some of his generals.

But in remarks prepared for delivery at Thursday's House Armed Services Committee hearing, Gates offered assurances that the military command stands behind the president.

"Your senior professional military officers in Iraq and in Washington believe in the efficacy of the strategy outlined by the president last night," Gates' prepared testimony said.

Gates will face a skeptical audience, particularly from new House Armed Services Committee Chairman Ike Skelton (news, bio, voting record), D-Mo. In a statement late Wednesday, Skelton dismissed Bush's plan as "three and a half years late and several hundred thousand troops short."

Looking to display party unity, House and Senate Democratic leaders issued a joint statement following the speech, asserting that Bush's plan places an increased burden on a stretched military and "endangers our national security."

In an effort to isolate Bush and his war plan, Democrats planned to seek bipartisan support for a resolution that would place Congress on record opposing the troop increase. That effort, though, also underscored Democratic divisions on whether to undo Bush's plan with tougher legislative measures.

House Republican Leader John Boehner (news, bio, voting record), R-Ohio, chided Democrats for offering no alternative to Bush's plan. "If Democrat leaders don't support the president's plan," he said, "it's their responsibility to put forward a plan of their own for achieving victory."

While Republican House and Senate leaders stood with Bush on Wednesday, other Republican lawmakers bluntly rejected the president's strategy. Among those voicing opposition to the troop buildup were Sens. Olympia Snowe (news, bio, voting record) and Susan Collins (news, bio, voting record) of Maine, Sam Brownback (news, bio, voting record) of Kansas, Norm Coleman (news, bio, voting record) of Minnesota and Chuck Hagel (news, bio, voting record) of Nebraska.

"This is a dangerously wrong-headed strategy that will drive America deeper into an unwinnable swamp at a great cost," said Hagel, a Vietnam War veteran and potential GOP presidential candidate.

Hagel is among the senators Rice will face when she testifies Thursday before the Senate Foreign Relations Committee. The committee is also a perch for a handful of potential Democratic presidential candidates, including Sen. Barack Obama (news, bio, voting record) of Illinois and committee chairman Joseph Biden (news, bio, voting record) of Delaware.

Rice can expect to be quizzed on diplomatic outreach to Iran and Syria, two U.S. adversaries that have significant influence in Iraq. The bipartisan Iraq Study Group, in a report last month, recommended the Bush administration directly engage both countries and seek their help in the war.

The president has declined, citing Iran's efforts to arm itself with nuclear weapons and Syria's support of Hezbollah and Hamas, which the U.S. deems terrorist organizations.

Instead, Bush in his speech accused Iran and Syria of "allowing terrorists and insurgents to use their territory to move in and out of Iraq."

"We will interrupt the flow of support from Iran and Syria," he said. "And we will seek out and destroy the networks providing advanced weaponry and training to our enemies in Iraq."

Rep. Dennis Kucinich, D-Ohio, a longtime opponent of the war, said he feared Bush was setting the stage for a wider regional war. "Isn't one war enough for this president--" he said.

Besides boosting US military presence in Iraq, Bush said the United States planned to hold Iraqi government to a series of benchmarks, though he did not say what the consequences for the Iraqis would be. Among those steps:

-- The Iraqi government would take over security in all of the country's provinces by November.

-- Iraq would pass legislation to share oil revenue among all of Iraq's ethnic groups.

-- The Iraqi government would spend US$10 billion of its own money on reconstruction.

-- A free hand, promised by Prime Minister Nouri al-Maliki, for Iraqi and American forces to enter any neighborhood seen as responsible for sectarian violence.