WASHINGTON - Sen. John Thune, R-S.D., said Tuesday that he is waiting to see the results of a progress report on the war in Iraq before making any new assessments on the conflict.

The war's top commander, Gen. David Petraeus, is due to present a September report to Congress on whether the troop buildup ordered by President Bush earlier this year is working.

"I am willing to give this until the report from Gen. Petraeus in September," Thune said. "In fairness, we have to give this strategy a chance to work."

But he added that he doesn't see the war as open-ended.

"I hope the administration is beginning to think about and formulate Plan B in the event the progress report isn't good, and most conclude at this point that that will be a mixed report at best," Thune said.

After a trip to the country last December, Thune said he thought U.S policy would change.

"We can't continue doing what we're doing," he said in December. "We're spinning our wheels, and we've got to turn the corner on this thing, and we've got to do it, I would say, in the next six months."

The next month, Bush announced he would increase troops by more than 20,000 to quell the country's near-anarchy.

Thune said then that the plan was constructive and Bush had rightly acknowledged a change in direction was needed.

"We had to make one last shot at getting this right," Thune said Tuesday.

Thune's comments come as the Senate faces several votes on the war next week. Democrats are expected to offer several Iraq amendments to a wide-ranging defense authorization bill, including efforts to cut off funding for the war and set hard deadlines for withdrawal.

Thune, who is expected to vote with his party in opposition to those efforts, said some Democrats are trying to embarrass Bush and also trying to prove to their anti-war base that they are "fighting the good fight."

"There's a very broad partisan divide, unfortunately," he said.

At the same time, he predicted that some of his Republican colleagues would be moderating their language with regard to Iraq.

That has already started to happen.

Breaking with the president, Sen. Richard Lugar, R-Ind., a widely respected former Foreign Relations Committee chairman, said last week that the military buildup was not working and the U.S. military presence in Iraq should be trimmed.

Sen. George Voinovich, R-Ohio, agreed. And Sen. John Warner, R-Va., a senior voice on military matters, suggested more GOP defections were likely after Congress' Fourth of July break.

Thune said he is open to new strategies.

"My thinking on this is going to be shaped by how to we keep Americans safe and secure, and how do we keep Iraq from becoming a staging ground from which terrorist organizations can launch attacks against our allies in the region, or worse yet against the United States," he said. "If there are other strategies that can accomplish that goal, that we haven't employed yet, I'm certainly open to those."