It was the fifth speech in less than three weeks, where the president laid out his plan for victory in Iraq, reports CBS News senior White House correspondent Bill Plante.
"I know that some of my decisions have led to terrible loss — and not one of those decisions has been taken lightly," Mr. Bush declared in a televised speech to the nation Sunday, his first from the Oval Office since announcing the invasion of Iraq in March 2003.
"It was probably the best speech he's ever given on Iraq because it was so realistic. This was one speech on Iraq not delivered from Mount Disneyland," University of Virginia political analyst Larry Sabato told CBS Radio News.
"He admitted that the past to the present has been strewn with mistakes and misjudgments, by him and by his key people. That's very significant," Sabato said.
"I think that was a very important thing for him to do. He's been a little bit more humble these days," said CBS News correspondent Gloria Borger.
At a, Mr. Bush also acknowledged that a prewar failure of American intelligence — claiming that Saddam Hussein possessed weapons of mass destruction — has complicated the United States' ability to confront other potential emerging threats such as Iran.
"Where it is going to be most difficult to make the case is in the public arena," Mr. Bush said. "People will say, if we're trying to make the case on Iran, 'Well, if the intelligence failed in Iraq, therefore, how can we trust the intelligence on Iran?'"
The president held out the promise Sunday night that when the Iraqi military gains strength and self-government moves forward, "it should require fewer American troops to accomplish our mission. I will make decisions on troop levels based on the progress we see."
The language was not specific enough for President Bush's critics.
"While I appreciate the president's increased candor, 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 when the troops "can begin to come home," said Senate Democratic leader Harry Reid of Nevada.
His House counterpart, Rep. Nancy Pelosi, D-Calif., said: "Tonight the president acknowledged more of the mistakes he has made in Iraq, but he still does not get it. Iraq did not present an imminent threat to the security of the United States before he began his war of choice."
The president said that despite setbacks, "Not only can we win the war in Iraq — we are winning the war in Iraq."
There is a difference, he said, between "honest critics who recognize what is wrong, and defeatists who refuse to see that anything is right."
That drew a rebuttal from Sen. Edward M. Kennedy, D-Mass.
"It's wrong for him to silence his critics by calling them defeatists," said Kennedy. "Every American — including those that thought this war should never have been fought — understands that we have no choice for own security but to win in Iraq."
Mr. Bush should acknowledge, "as his own generals do, that the Iraq war has emboldened the terrorists and increased their ranks," Kennedy said.
Critics also said a change in direction is essential.
Iraqis must be told the United States will reconsider its presence unless the new constitution is revised to give the minority Sunni Arab community a stake in running the country, said Sen. Carl Levin, D-Mich.
"They've got to share power, they've got to share oil resources," said Levin, senior Democrat on the Senate Armed Services Committee. There can be a significant withdrawal of U.S. troops only if there are enough capably trained Iraqi soldiers by the end of 2006, he said.
In his speech, the president said it is important "for every American to understand the consequences of pulling out ... before our work is done. We would abandon our Iraqi friends and signal to the world that America cannot be trusted to keep its word."
"He needs to understand that our brave servicemen and women won a resounding victory in the initial military operation, and their task is now largely over," said Sen. Russ Feingold, D-Wis.
Mr. Bush said some look at Iraq and conclude that "the war is lost," but "not even the terrorists believe it. We know from their own communications that they feel a tightening noose — and fear the rise of a democratic Iraq."
Sen. John Warner, R-Va., Armed Services Committee chairman, said President Bush's speech "was a high-water mark in his acknowledgment that mistakes have been made and that he has to accept his share of the blame.
"But he remains resolute, as he should, in continuing our help to the Iraqi people so that they can achieve a self-sufficient government and become a truly sovereign nation," Warner added.
A random survey Monday morning of New Yorkers showed a split.
"I believe the president has been wrong since the beginning. We support our troops, but he's got to get them out of there. It's a quagmire. It's not going to win anything," one told CBS News' Greg Solfanelli.
"I think we have to finish the job. It's a whole different type of global conflict than we've ever had before, and he's right on the mark to stick with it. He's a man of his word. Others I think are just running and cowardly," said another.
"Those who that supported the war clearly had their thoughts reinforced. Those of us who opposed it were a little surprised at his arrogance," Rep. Charles Rangel, D-N.Y., told CBS Radio News. "It reminds me of an old Peggy Lee song, 'Is That All There Is.'"
Mr. Bush's Oval Office address followed a string of weekend attacks by insurgents in Iraq that pierced three days of relative calm. It also topped off an 18-day span in which Bush made five speeches conceding setbacks amid progress in Iraq.