U.S. Rep. Neil Abercrombie predicts a Pentagon progress report on Iraq next month will say the "surge" of 30,000 U.S. troops has helped security, but that the start of troop withdrawals shortly thereafter is likely.

Growing constituent unhappiness with the four-year-old war is leading greater numbers of Republican politicians to oppose it as they look ahead to 2008 elections, Abercrombie said.

"They've got to have something that they can take back to their individual constituencies (regarding a change in the war) no matter how Republican those constituencies are," the Hawai'i Democrat said.

Abercrombie yesterday spoke to the Honolulu Rotary Club at the Royal Hawaiian Hotel.

Army Gen. David Petraeus, the top-ranking U.S. commander in Iraq, and U.S. Ambassador to Iraq Ryan Crocker are expected to testify to Congress Sept. 11 or 12 on the progress of the war in Iraq.

The report is expected to be a milestone in the war, with President Bush repeatedly saying he would listen to commanders on the ground.

"I think their goal is just to say they've had some measurable progress, but that the Iraqis really haven't held up their end of it, and so we need to start withdrawing," Abercrombie said. "And I think once that starts, that will surge. The second you start moving (troops) out, it will be like Vietnam — they are all gone. The question is, how fast?"

Petraeus has said the surge will end, and the No. 2 commander in Iraq recently said the surge troops are scheduled to leave after 15 months, meaning departures between April and August of next year.

How many troops would remain, and for how long, also is unclear. There are 162,000 U.S. troops in Iraq.

In a speech today, the president is expected to say U.S. forces are making progress in Iraq and to question whether Washington will "pull the rug out from under them."

But in a joint statement, Sens. John Warner, R-Va., and Carl Levin, D-Mich., said while the surge is "having measurable results" and provided breathing room for Iraqi politicians to make compromises that are essential for a political solution in Iraq, "we are not optimistic about the prospects for those compromises."

A bill co-written by Abercrombie that calls for the Bush administration to report to Congress on its planning for troop reductions in Iraq passed the Senate Armed Services Committee by a 55-2 vote.

Reach William Cole at wcole@honoluluadvertiser.com.