WASHINGTON — President Bush declared Sunday evening that the United States is winning the war in Iraq, but he warned doubting Americans that the path to victory remains riddled with violence and uncertainty. He vowed not to fully withdraw troops or retreat until democracy is established in the country.

In a prime-time address from the White House, the president conceded that his administration had underestimated the difficulty of achieving victory and he vowed to listen to "honest criticism" of his Iraq policy. With a fresh air of contrition, he spoke directly to his detractors, whose ranks have grown since the war began nearly three years ago.

"I have heard your disagreement and I know how deeply it is felt," Bush said, using the Oval Office as a backdrop for the first time since he announced the Iraq invasion on March 19, 2003. "Yet now there are only two options before our country — victory or defeat. And the need for victory is larger than any president or political party because the security of our people is in the balance."

Raising his hands for emphasis, he added: "I do not expect you to support everything I do, but tonight I have a request: Do not give in to despair and do not give up on this fight for freedom."

The Bush administration is seeking to rebuild support for its mission after enduring one of the most politically challenging points of the presidency, with nearly half of the American people convinced the war was a mistake. More than 2,150 American soldiers have died and a growing number of Democrats and Republicans have called on Bush to be more forthcoming about his strategy in Iraq.

The Sunday night speech, broadcast by the major U.S. television networks, was the latest chapter in a White House campaign designed to turn the tide of public opinion. Since he released a detailed plan for victory in Iraq a month ago, Bush has delivered four major speeches, taking the rare step of admitting mistakes even as he renews his commitment to defeating the insurgency.

"Some look at the challenges in Iraq and conclude that the war is lost and not worth another dime or another day," Bush said. "I don't believe that. Our military commanders do not believe that. Our troops in the field, who bear the burden and make the sacrifice, do not believe that America has lost."

During a 17-minute speech, Bush pointedly acknowledged that the chief rationale for war — disarming Iraq's suspected weapons of mass destruction program — was based on incorrect intelligence. It was one of his most direct statements on the controversial subject, delivered to an audience of millions.

"Much of the intelligence turned out to be wrong and as your president, I am responsible for the decision to go to Iraq," Bush said. "Yet it was right to remove Saddam Hussein from power."

While Bush hailed the success of last week's parliamentary elections, in which an estimated 10 million Iraqis cast ballots, he said the violence would not end until a democracy is fully established and the Iraqis could govern and protect themselves. Reviving the economy and rebuilding the infrastructure has faced repeated setbacks, Bush said, but he vowed to finish the mission.

"To retreat before victory would be an act of recklessness and dishonor," Bush said, "and I will not allow it."

An anti-war sentiment has steadily grown throughout the year, but the White House began responding after Rep. John Murtha, D-Pa., a decorated Vietnam veteran, called for the immediate withdrawal of troops. While not all Democrats have joined the call, his impassioned plea changed the tone of the debate.

The president, while not mentioning Murtha or other critics by name, argued that pulling forces from Iraq now would be dangerous to American security.

"We will continue to listen to honest criticism and make every change that will help us complete the mission," Bush said. "Yet there is a difference between honest critics who recognize what is wrong and defeatists who refuse to see that anything is right."

Sen. Edward Kennedy, D-Mass., said after the speech that the president was wrong "to attempt to silence his critics by calling them defeatists."

Senate Minority Leader Harry Reid, D-Nev., praised the president for his recent candor on Iraq, but added: "Too much of the substance remains the same and the American people have still not heard what benchmarks we must meet along the way to know that progress is being made and that our brave troops can begin to come home."

Hours before Bush spoke, Vice President Dick Cheney secretly traveled to meet troops in the Middle East, where he declared: "Iraq's looking good." Other senior administration officials also delivered speeches and appeared on Sunday talk shows to talk about progress in Iraq.