President Bush on Thursday challenged lawmakers to prove their support for troops in Iraq by agreeing to more war spending without attaching a timeline for withdrawal or any other conditions.

Bush used a fundraising speech for House Republican candidates to push back on Democrats opposed to his Iraq plans.

The House is nearing a vote on a bill that would require a troop withdrawal from Iraq by Sept. 1, 2008. It is part of a $124 billion spending bill that includes $95.5 billion for the wars in Iraq and Afghanistan.

Hours before Bush spoke, the House Appropriations Committee approved the bill in a near party-line vote.

"Some in Congress are using this bill as an opportunity to micromanage our military commanders, or to force a precipitous withdrawal in Iraq, or threaten vital funding for Iraqi security forces to fund projects that have nothing to do with the war on terror," Bush said at a dinner hosted by the National Republican Congressional Committee.

"I believe that members of Congress were sincere when they say they support our troops, and now is the time for them to show that support," the president said. "Our men and women in uniform are risking their lives."

A successful House vote would be a stern challenge to Bush, who has threatened to veto such a bill. The matter looks unlikely to get that far, however, as the Senate has shown no indication it would support such a move.

Bush, in fact, heralded the Senate's Thursday rejection of a less-sweeping anti-war measure.

It would have required a troop withdrawal to begin within 120 days, with a goal of completion by March 31, 2008.

"I thank the Republicans and Democrats who voted down that resolution," Bush said.

"Many of those members know what I know: that if American forces were to step back from Baghdad now, before the capital city is more secure, the scale and scope of attacks would increase and intensify," he said.

Democrats won control of the House and Senate in November, fueled in large part by the public's weariness with war. Yet asserting influence is tricky for Democrats. They have the power of the purse but don't want to undermine the troops.

Bush, in turn, must be careful. He needs the Democrats if he is to have any chance of salvaging his agenda on other issues.

Anchored by his appearance, Thursday's dinner raised more than $6.2 million for Republican House candidates.

Bush also used the campaign speech to defend his "no child left behind" education plan, which has lost support on Capitol Hill. On Thursday, dozens of conservative members of Bush's party announced they want to overhaul the law, which they consider intrusive.

Bush said flatly that the law is working. "I believe strongly in local control of schools," he said. "But I also believe in raising standards and holding schools accountable for achieving results."