Democrats stepped up pressure for President Bush to halt his Iraq troop buildup as the president warned Congress against undercutting his military strategy.
Representative John Murtha, who chairs the House panel that oversees military spending, said he planned to restrict war funding in a way that would effectively stop the 21,500 US troop buildup.
Senate Democratic Leader Harry Reid has scheduled a new vote to confront Mr Bush over Iraq.
The political manoeuvring came as a new poll showed public support for the Iraq war continuing to fall, with 53 per cent of Americans believing the United States should bring its troops home as soon as possible.
But Mr Bush, in an address in Washington, warned US legislators against taking action that would restrict his $93.4 billion emergency troop funding measure.
"Our men and women in uniform are counting on their elected leaders to provide them with the support they need to accomplish their mission," he said. "Republicans and Democrats have a responsibility to give our troops the resources they need."