The top US commander in Iraq, Gen David Petraeus, faced a tough challenge today from both Republicans skeptical about war strategy and Democrats who want a swifter withdrawal of American troops.
The bipartisan grilling of Gen Petraeus and US ambassador to Baghdad Ryan Crocker in Congress raised questions about whether President George W. Bush could count on enough of his Republican colleagues for help in staving off Democratic demands for a faster pullout.
Mr Bush is expected to give a speech later this week on Iraq but has shown no signs of ordering drastic troop withdrawals.
Gen Petraeus insisted progress was being made under the Bush strategy of temporarily building up troops this year to allow time for political reconciliation, an approach which is being strongly challenged in Washington.
"Though we both believe this effort can succeed, it will take time," Gen Petraeus told the Senate Foreign Relations committee.
Republican Sen Chuck Hagel of Nebraska, asked: "Are we going to continue to invest American blood and treasure at the same rate we're doing now? For what? The president said, 'Let's buy time.' Buy time? For what?"
Many tens of thousands of Iraqis and more than 3,700 U.S. troops have died since the war began in 2003.
Sen Richard Lugar of Indiana, the top Republican on the committee, told Petraeus that Bush's troop increase "must not be an excuse for failing to prepare for the next phase of our involvement in Iraq, whether that is partial withdrawal, a gradual redeployment or some other option."
Sen Barack Obama of Illinois, one of eight candidates for the Democratic presidential nomination, said progress in Iraq had been only modest under the buildup of 30,000 extra troops ordered by Mr Bush in January.
"We have now set the bar so low that modest improvement in what was a completely chaotic situation, to the point where now we just have the levels of intolerable violence that existed in June of 2006, is considered success. And it's not," he said.
"This continues to be a disastrous foreign policy mistake."
Mr Obama also complained that the hearing was taking place on the sixth anniversary of the Sept. 11 attacks. He said it perpetuated "this notion that somehow the original decision to go into Iraq was directly related to 9/11."
Gen Petraeus repeated his plan - outlined yesterday - to gradually pull out the extra forces and bring troop levels back down to about 130,000 by next summer.
But Gen Petraeus said he could not predict how quickly troop levels would fall after the summer and his force should still protect the Iraqi population, not focus solely on handing over to Iraqi forces and conducting counter-terrorism missions.
As during his testimony to House of Representatives committees yesterday, he was interrupted several times by shouts from anti-protesters.