The tone at today's daylong hearing before the Senate Foreign Relations and Armed Services committees was far different from yesterday's House of Representatives session and marked by much sharper attacks on President Bush's entire Iraq policy.

Bush ordered 30,000 more U.S. troops to Iraq in January for six months to tamp down violence so that Iraqi politicians would have a chance to forge compromises and create a stable government for all ethnic groups. This week, Petraeus asked Congress to give that approach more time.

He said the surge of 30,000 additional troops can be rolled back by mid-July 2008 — 18 months after Bush ordered the troop increase to begin. That would still leave 130,000 U.S. troops in Iraq more than five years after they invaded. Petraeus said he couldn't decide on further withdrawals before March. Bush is expected to endorse Petraeus' plan in a televised speech to the nation on Thursday night.

Sen. Robert Byrd, D-W.Va., told Petraeus and Crocker that every few months, "someone from the administration comes up and says, 'Just give us six or 12 more months and things will look better.' You've talked about military success, but by the president's own reckoning, that success is meaningless without political reconciliation. Are six months or 12 months really going to make a difference on the big questions? Why should we keep giving you more and more time?"

Petraeus said that violence against Iraqi civilians was down recently, but remains high. Crocker acknowledged that Iraqis have made no real progress toward a national settlement but are taking some steps in the right direction.

Sen. Lisa Murkowski, R-Alaska, quoted Petraeus' own words back to him — that American forces could hand over responsibility to Iraqis "as the situation and Iraqi capabilities permit."

"This sounds identical to what President Bush has been saying all along, that U.S. forces will draw down as the Iraqis are able to stand up," Murkowski said. "Are we continuing the same path we have laid out before, entirely reliant on the ability of the Iraqis to come together to achieve that political reconciliation, and unless they are able to do that, we are not able to execute your recommended force reductions?"

Petraeus said that a transition to Iraqi control has taken place in some places already. He said that U.S. forces were trying to speed things up, but couldn't proceed faster than conditions allow or they'd be "rushing to failure."

Sen. Hillary Clinton, D-N.Y., a presidential candidate, said Bush ordered Petraeus and Crocker to implement "what many of us see as a failed policy."

She said that civilian deaths and car bombings in Iraq have risen and that American casualties have been greater in every month of 2007 than they were in the same month of 2006. Meantime, Osama bin Laden, the mastermind of the Sept. 11 attacks, remains at large and his terror network is gaining strength in Pakistan, she said.

"The reports that you provide to us really require the willing suspension of disbelief," Clinton said.

Sen. Joseph Biden, D-Del., chairman of the Foreign Relations Committee and also a presidential candidate, was dismissive of the whole strategy.

"Simply put, Iraqis — both Sunnis and Shiites — still live every day in deadly fear of each other, and until their leaders agree on some way to share power peacefully, that fear is not going to go away and Iraq will not find stability," Biden said.

Biden said he didn't think Iraq could reach a settlement "in the lifetime of any of us." Therefore, he said, sustaining the surge would "put more American lives at risk, in my view with very little prospect of success, and I don't think that is conscionable."

Sen. John Warner of Virginia, one of the most influential Republicans on national security matters, asked Petraeus if his recommendations would make America safer. Petraeus initially evaded a direct answer, saying:

"Sir, I believe that this is indeed the best course of action to achieve our objectives in Iraq."

Warner asked again.

"Sir, I don't know actually," Petraeus said. "I have not sat down and sorted out in my own mind. What I have focused on and been riveted on is how to accomplish the mission of the Multinational Force-Iraq."

Later, when Sen. Evan Bayh, D-Ind., asked him again about the exchange, Petraeus said the answer was yes, because the United States has national interests in Iraq and success there is important for national security.

Sen. John Sununu, R-N.H., asked Crocker if he had confidence that Iraqis would effectively use the $10 billion in oil resources that they promised to spend for reconstruction.

Crocker said that Iraq's government has "mechanisms to monitor waste, fraud and mismanagement."

Do they work, Sununu asked?

"To a degree," Crocker replied.

Sen. Barack Obama, D-Ill., a presidential hopeful, said that if Americans had understood at the war's outset that it would cost thousands of American lives and $1 trillion, that it would increase terrorist recruitment and strengthen Iran, that the global al-Qaida network would emerge stronger, and that living standards in Iraq would sink lower, "I think most people would have said, 'That's a bad deal.' "

Sen. Richard Lugar of Indiana, another leading Republican voice on foreign affairs, said the discussion must move beyond whether there'd been progress in Iraq and start to focus on a better strategy to get Iraqis to settle their differences.

"The risk is that our efforts are comparable to a farmer expending his resources and efforts to plant a crop on a flood plain, without factoring in the probability the waters may rise," Lugar said.

Diplomacy is essential for success, Lugar argued. "If we have not made substantial diplomatic progress by the time a post-surge policy is implemented, our options will be severely constrained, and we will be guessing at a viable course in a rapidly evolving environment."