Top House Democrats retreated from an attempt to limit President George W. Bush's authority for taking military action against Iran as the leadership concentrated on a looming confrontation with the White House over the Iraq war.

Officials said Monday that House Speaker Nancy Pelosi and other members of the leadership had decided to strip from a major military spending bill a requirement for Bush to gain approval from Congress before moving against Iran.

Conservative Democrats as well as lawmakers concerned about the possible impact on Israel had argued for the change in strategy.

The developments occurred as Democrats pointed toward an initial test vote in the House Appropriations Committee on Thursday on the overall bill, which would require the withdrawal of U.S. combat troops from Iraq by Sept. 1, 2008, if not earlier. The measure provides nearly $100 billion to pay for fighting in two wars, and includes more money than the president requested for operations in Afghanistan and to alleviate what Democrats called training and equipment shortages.

The White House has issued a veto threat against the bill, and Vice President Dick Cheney attacked its supporters in a speech, declaring they "are telling the enemy simply to watch the clock and wait us out."

House Republican Leader John Boehner of Ohio issued a statement that said Democrats should not count on any help passing their legislation. "Republicans will continue to stand united in this debate, and will oppose efforts by Democrats to undermine the ability of General Petraeus and our troops to achieve victory in the Global War on Terror," he said.

Top Democrats had a different perspective.

Pelosi issued a written statement that said the vice president's remarks prove that "the administration's answer to continuing violence in Iraq is more troops and more treasure from the American people."

Senate Majority Leader Harry Reid said in a statement that America was less safe today because of the war. The president "must change course, and it's time for the Senate to demand he do it," he added.

The Iran-related proposal stemmed from a desire to make sure Bush did not launch an attack without going to Congress for approval, but drew opposition from numerous members of the rank and file in a series of closed-door sessions last week.

Rep. Shelley Berkley, a Nevada Democrat, said in an interview there is widespread fear in Israel about Iran, which is believed to be seeking nuclear weapons and has expressed unremitting hostility toward the Jewish state.

"It would take away perhaps the most important negotiating tool that the U.S. has when it comes to Iran," she said of the now-abandoned provision.

"I didn't think it was a very wise idea to take things off the table if you're trying to get people to modify their behavior and normalize it in a civilized way," said Rep. Gary Ackerman of New York.

Several officials said there was widespread opposition to the proposal at a closed-door meeting last week of conservative and moderate Democrats, who said they feared tying the hands of the administration when dealing with an unpredictable and potentially hostile regime in Tehran.

Public opinion has swung the way of Democrats on the issue of the war. More than six in 10 Americans think the conflict was a mistake -- the largest number yet found in AP-Ipsos polling.

But Democrats have struggled to find a compromise that can satisfy both liberals who oppose any funding for the military effort and conservatives who do not want to unduly restrict the commander in chief.

"This supplemental should be about supporting the troops and providing what they need," said Rep. Dan Boren, an Oklahoma Democrat, on Monday upon returning from a trip to Iraq. Boren said he plans to oppose any legislation setting a clear deadline for troops to leave.

In his speech, Cheney chided lawmakers who are pressing for tougher action on Iran to oppose the president on the Iraq War.

"It is simply not consistent for anyone to demand aggressive action against the menace posed by the Iranian regime while at the same time acquiescing in a retreat from Iraq that would leave our worst enemies dramatically emboldened and Israel's best friend, the United States, dangerously weakened," he said.