Biden challenged Rice to acknowledge administration mistakes on Iraq and said he would vote for her confirmation, but only with "some frustration and reservation."

The Delaware senator, zeroing in on U.S. policy in Iraq as he had during Tuesday's initial hearing, accused the administration of giving shifting reasons to justify the war to oust Saddam.

Rice had steadfastly refused Tuesday to say when U.S. forces might be withdrawn from Iraq. And on Wednesday, Biden cited various rationales for the war, saying "you danced around it, stuck to the party line."

He told Rice that acknowledging mistakes — such as the claim that Saddam had weapons of mass destruction and was poised to use them — should not be considered "a sign of weakness."

Sen. Lincoln Chafee, R-R.I., meanwhile, urged Rice to consider reconciliation with Iran, which he said was about as repressive as China was when the Nixon administration approached Beijing for better relations.

But Rice said, "It is really hard to find common ground with a government that thinks Israel should be extinguished," supports terror groups and is undercutting U.S. peace efforts in the Middle East.

More than 1,365 members of the U.S. military have died since U.S. troops led an invasion of Iraq in March 2003.

But Rice has declined to estimate when even some of the 150,000 U.S. troops may return home.

"I am really reluctant to try to put a timetable on that, because I think the goal is to get the mission accomplished," she had said Tuesday, "and that means that the Iraqis have to be capable of some things before we lessen our own responsibility," she said.

The 18 members of the committee were eager to quiz Colin Powell's designated successor, although Sen. Richard Lugar, R-Ind., the panel's chairman, planned a vote following the hearing.

Committee approval would send the nomination to the Senate where confirmation appears certain — despite unease, especially among Democrats, about reasons Bush, Powell, Rice and others in the administration gave for going to war in March 2003 and how they are dealing with a deadly postwar insurgency.

At the State Department, Powell planned a farewell speech at midday, while employees were told to gather Friday in the lobby to welcome Rice on what would be her first day in charge of U.S. foreign policy.

Her positions on the war did not stem blistering criticism from Democratic senators.

Sen. John Kerry, who made Bush's management of postwar Iraq an issue in his losing presidential campaign, told Rice Tuesday that "the current policy is growing the insurgency and not diminishing it."

"This was never going to be easy," Rice said in response. "There were going to be ups and downs."

She said that after the Iraqis have voted on Jan. 30 for a transitional assembly, the Bush administration would conduct a review.

"We need to be patient," she told Kerry.