WASHINGTON — A leading Iraq war opponent threatened yesterday to try prohibiting any American military action against Iran without congressional sanction as House Republicans used military veterans within their ranks to oppose a resolution renouncing President Bush’s Iraq troop buildup.

Rep. John Murtha, a Democrat of Pennsylvania, said he would seek to tie future deployments in Iraq to troops meeting high standards of training and getting enough rest between combat tours. Mr. Murtha said he believes the Army may have no units that can meet those standards, meaning that Mr. Bush’s attempt to send 21,500 more troops to Iraq would be effectively thwarted.

Mr. Murtha, who has been among Congress’s foremost opponents of Iraq war policy, also said he is considering attaching a provision to a looming war spending bill that would bar American military action against Iran without congressional approval.

“We don’t have the capability of sustaining a war in Iran,” Mr. Murtha, chairman of the House panel that oversees military spending, said in a videotaped online interview.

Mr. Bush, in a speech on the war on terror, also weighed in on the House resolution, saying it comes just weeks after the Senate unanimously confirmed General David Petraeus as the commander of American forces in Iraq.

“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,” Mr. Bush said.

Meanwhile, Senator Reid, who is the majority leader, said the Senate will hold another test vote Saturday on the Iraq resolution.

The Senate has been unable to begin debate on Iraq for two weeks because of partisan bickering over the procedural terms. Democrats would need 60 votes to bring the resolution back up when Congress returns after a week’s recess.

“We demand an up-or down vote on the resolution that the House is debating as we speak,” said Mr. Reid, a Democrat of Nevada.

Earlier, Senator Specter, a Republican of Pennsylvania, complained that the Senate “is about to become irrelevant,” adding, “What we have here is close to anarchy.”

Back in the House, Rep. Sam Johnson, a Republican of Texas and a former prisoner of war in Vietnam, led a group of military veterans among the GOP ranks in protesting the House resolution disapproving the deployment of the additional American forces to the battlefields of Iraq. He was joined by other Vietnam War veterans in saying such opposition from Washington sends a signal of retreat in the war on terrorism.

“This nonbinding resolution serves no purpose other than pacifying the Democrats’ political base and lowering morale in our military,” said Rep. Geoff Davis, a Republican of Kentucky, a West Point graduate who was a flight commander with the Army’s 82nd Airborne.

The Democratic whip, Rep. James Clyburn of South Carolina, on the third day of House debate on the resolution, countered that 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,” Mr. Clyburn said.

It appeared certain that Democrats, who took control of Congress last fall in no small part because of growing public disenchantment with the war, would carry the day in approving the resolution when a vote takes place on Friday. On Wednesday, 10 House Republicans gave speeches indicating they would vote for the resolution.

Mr. Clyburn estimated that between 15 and 20 Republicans would join Democrats in voting for the resolution. He expected to lose only two or three Democrats.

The resolution is nonbinding, but Democrats already are turning to the more consequential debate next month over Bush’s request for nearly $100 billion more for the war, a request that promises to become a new battleground over his Iraq policy.

The House speaker, Rep. Nancy Pelosi, has said the Democratic resolution was the first step in a longer campaign to end America’s participation in the nearly four-year-old conflict.

In a letter to the president on Wednesday, Ms. Pelosi and Mr. Reid said, “thousands of the new troops” being sent into Iraq “will apparently not have the armor and equipment they need to perform the mission and reduce the likelihood of casualties.”