Washington ? The House Republican leader said Sunday that GOP support could waver if President Bush’s Iraq war policy does not succeed by the fall.

House Minority Leader John Boehner, R-Ohio, said Bush’s troop increase deserves a shot and that funding should continue even if benchmarks for success are not met. A senior Democrat said it would be “ridiculous” not to condition war money upon a troop withdrawal.

“We don’t even have all of the 30,000 additional troops in Iraq yet, so we’re supporting the president. We want this plan to have a chance of succeeding,” Boehner said.

“Over the course of the next three to four months, we’ll have some idea how well the plan’s working. Early signs are indicating there is clearly some success on a number of fronts,” he said.

But, he added, “By the time we get to September or October, members are going to want to know how well this is working, and if it isn’t, what’s Plan B?”

Thus far, Republicans have stood behind the president’s increasingly unpopular war policies, including the troop increase and an open-ended war commitment.

Yet Boehner’s comments were an acknowledgment of the concern expressed by some lawmakers in private that their support could further damage the party, which lost control of Congress in the November elections.

The senior Republican on the Senate Foreign Relations committee, Sen. Richard Lugar of Indiana, said Boehner is correct.

“General Petraeus will be back. He’ll make a report,” Lugar said of Gen. David Petraeus, commander of U.S. forces in Iraq. “Some things will go well. Some things will not go so well, but we’ll still have an obligation.”

The new Democratic leadership is pushing to begin pulling troops out of Iraq. Connecticut Sen. Chris Dodd, a Democratic presidential candidate, said congressional Republicans increasingly seem uneasy about Bush’s policies.

“So we may disagree politically here, but remember where the American public is on this issue: They want a change. They think we’re getting less secure, far more vulnerable today, than ever before, and they want a change in this policy,” he said.

Last week, Bush vetoed a $124 billion bill to provided money for Iraq and Afghanistan operations in part because it required troops to begin returning home by Oct. 1, saying the fixed date is unworkable.

Top White House aides are negotiating with Democratic leaders on a new war spending bill.

“It would be ridiculous to think that we’re going to just drop this fight,” said Democratic Rep. Charles Rangel of New York, chairman of the tax-writing House Ways and Means Committee. “This is not our fight. This is the American people’s fight. They asked us to send a message to the president.”