Pelosi, D-Calif., noted that Bush consistently said he supports a diplomatic resolution to differences with Iran "and I take him at his word."

At the same time, she said, "I do believe that Congress should assert itself, though, and make it very clear that there is no previous authority for the president, any president, to go into Iran."

Pelosi spoke in an interview in the Capitol as lawmakers plowed through a third day of marathon debate in the House on a non-binding measure opposing the administration's plan to increase troop strength in Iraq — and as Democrats readied a more provocative challenge to the president.

That included drafting legislation to require the Pentagon to meet certain standards for training and equipping the troops, as well fixing the time that military units must be given at home between deployments. "That stops the surge (in troops) for all intents and purposes, because ......they cannot sustain the deployment," said Rep. John Murtha of Pennsylvania, who said he would attach the conditions to legislation providing nearly $100 billion for the military.

Republicans quickly fired back. Rep. John Boehner of Ohio, the GOP leader, issued a statement saying the plan would "pull the rug out from under American troops in the combat zone by cutting off their reinforcements and forcing them to face the enemy without our full support."

Across the Capitol, Senate Majority Leader Harry Reid unexpectedly announced plans to hold a test vote on Saturday on the same non-binding measure critical of the troop increase that was making its way through the House.

Partisan bickering has prevented a Senate vote so far, with Republicans insisting on equal treatment for an alternative that rules out the "elimination or reduction of funds for troops in the field."

Pelosi and other Democrats have said approval on the non-binding measure would mark the first step in an effort by the new Democratic-controlled Congress to force Bush to change course in a war that has killed more than 3,100 U.S. troops.

Bush administration officials and their allies are resigned to House passage of the resolution and have worked in recent days to hold down defections by GOP lawmakers.

But Bush, who has challenged lawmakers not to cut off funds for the troops, took a swipe at his critics during the day.

"This may become the first time in the history of the United States Congress that it has voted to send a new commander into battle and then voted to oppose his plan that is necessary to succeed in that battle," the president said.

The Senate unanimously confirmed Lt. Gen David Petraeus last week to take over as the top U.S. commander in Iraq.

Bush said at a news conference Wednesday there is no doubt the Iranian government is providing armor-piercing weapons to kill American troops in Iraq. But he backed away from claims the top echelon of Iran's government was responsible.

Administration critics have accused the president of looking for a pretense to attack the Islamic republic, which is also at loggerheads with the United Nations about what Tehran says is a nuclear program aimed at developing energy for peaceful purposes.

Defending U.S. intelligence that has pinpointed Iran as a hostile arms supplier in Iraq, Bush said, "Does this mean you're trying to have a pretext for war? No. It means I'm trying to protect our troops."

Bush has asked Congress to approve $100 billion for the wars in Iraq and Afghanistan. Congressional Democrats are hoping to insert provisions that would make it harder for the administration to follow through on its plan to deploy an additional 21,500 combat troops to Iraq.

Murtha, in a video aired on movecongress.org, a coalition of groups opposed to the war, said his proposals were designed with the safety and protection of the troops in mind.

The Pennsylvania Democrat also said the measure may be changed to prohibit any military action against Iran without specific congressional approval.

Asked about Murtha's remarks, Pelosi said, "I fully support that." She added that she would propose it as stand-alone legislation if it is not included in the bill that provides more money for the Iraq war.

Bush has said he intends to go ahead with the troop buildup regardless of non-binding expressions of disapproval in Congress.

But, Pelosi said, "I don't think that the president can completely ignore it."

She spoke down the hall from the House chamber, where Republicans and Democrats alternated turns at the microphone in a debate on the war.

"The enemy wants our men and women in uniform to think their Congress doesn't care about them," said Rep. Sam Johnson, R-Texas, who was a prisoner of war during Vietnam. "We must learn from our mistakes. We cannot leave a job undone like we left in Korea, like we left in Vietnam, like we left in Somalia," Johnson said.

Added Rep. Geoff Davis, R-Ky., a West Point graduate who was a flight commander with the Army's 82nd Airborne: "This non-binding resolution serves no purpose other than pacifying the Democrats' political base and lowering morale in our military."

When his turn came to speak, Rep. Lloyd Doggett, D-Texas., said, "There is a better way of protecting our troops than sending more of them to be killed."

Rep. James Clyburn of South Carolina, a member of the Democratic leadership, said the victory to be won in Iraq "is not a military conquest."

"The victory we seek is earned through the restoration of America's role as peacemaker, not warmonger," he said.