WASHINGTON — Senator Clinton squared off yesterday with her possible challenger for the White House in 2012, General David Petraeus, and came closer than any of her colleagues to calling the commander of the multinational forces in Iraq a liar.

Using blunter language than any other Democrat in the last two days, Mrs. Clinton told General Petraeus that his progress report on Iraq required “a willing suspension of disbelief.”

Referring to the charts General Petraeus brought to the House and Senate this week, Mrs. Clinton said, “Although the charts tell part of the story, I don’t think they tell the whole story.” She said the “bottom-up” political reconciliation was “anecdotal” and that the success in Anbar province, where sheiks turned on Al Qaeda, started before the surge.

At the end of her speech, Mrs. Clinton pointed to what she saw as a discrepancy in the general’s responses to questions from other senators about whether he would recommend that America keep 130,000 troops in Iraq a year from now if no progress was made toward national reconciliation.

“Don’t you think the American people deserve a very specific answer about what is expected from our country in the face of the failure of the Iraqi government and its failure to achieve its political agenda?” she asked.

General Petraeus responded calmly. “I don’t see quite as big a difference as you do,” he said. “I would be very hard pressed at that time to recommend a continuation of our current troop levels” if conditions on the ground were the same in a year as they are now. He added that Mrs. Clinton’s question was “quite a bit hypothetical.”

The senator’s reaction to the cautious optimism of America’s top general in Iraq is a pivot away from the position she took last month, when she conceded that American forces had achieved some security gains in Iraq, particularly in the Anbar province. She later backed away from those remarks after coming under fire from rival presidential campaigns and anti-war Democrats.

Mrs. Clinton has called for a firm date for withdrawal, but she also has made the case for keeping a reserve of troops in the Kurdish provinces of northern Iraq. In 2002, she famously rebuked protesters from Code Pink, the anti-war organization that tried to disrupt the hearings in Congress this week, when she voted in favor of the resolution authorizing the Iraq war.

Democratic leaders this month have hinted that they will not seek a withdrawal date as a condition of the temporary funding bills that expire this month. This may be in part because the White House already has agreed to withdraw some 30,000 soldiers by next summer, leaving 130,000, or the pre-surge troop levels, for the height of next year’s political season. President Bush will address the nation tomorrow and is expected to endorse the withdrawal strategy previewed this week by General Petraeus on Capitol Hill.

Mrs. Clinton was not the only Democratic presidential aspirant yesterday to find fault with the general’s testimony. Her chief rival for the nomination, Senator Obama of Illinois, zeroed in on claims that the surge strategy aided the rout sustained by Al Qaeda in Anbar, the development General Petraeus has said is the most important reason for optimism today in Iraq.

“I’m not sure that the success in Anbar has anything to do with the surge,” Mr. Obama said. “You yourself said it was political.”

The senator said General Petraeus was changing the definition of success in Iraq. “Changing the definition of success to stay the course with the wrong policy is the wrong course for our troops and our national security. The time to end the surge and to start bringing our troops home is now, not six months from now,” Mr. Obama said in his opening statement.

In response to a question from Senator McCain, a Republican of Arizona, on the doubts about the links between the Anbar success and the surge, General Petraeus said: “The success in Anbar province correctly is seen as a political success but it is a political success that is enabled by our forces that are enabled by additional forces sent to Anbar.” He added, “It would not have happened as quickly without the surge, and I don’t know if we could have capitalized on it without the surge.”

Other Democrats seeking the presidential nomination were also critical yesterday of General Petraeus. Senator Biden of Delaware, who until the end of 2006 was opposed to a precipitous withdrawal from Iraq, was particularly harsh. At the end of the hearing, he said he had not heard anything that persuaded him that the military was pursuing a new strategy as opposed to new tactics in Iraq.

In his opening statement, he warned, “The American people will not support an indefinite war whose sole remaining purpose is to prevent the situation in Iraq from becoming even worse.”

Senator Dodd of Connecticut spoke about his experience visiting a G.I. from his home state who had lost an eye. Mr. Dodd said the young man told him: “We will spend a month and a half to clear an area, and in an hour and a half things are back where they were before.”

General Petraeus responded by saying there were 165,000 American soldiers in Iraq with 165,000 different opinions.

Following the hearing, Mr. Dodd announced that he would not support any funding bill for Iraq or Afghanistan unless it included a date certain for withdrawal. “People are getting tired of hearing things are getting better. I don’t know anybody who believes that,” he said.