WASHINGTON — The Iraq war is re-emerging as a top campaign issue as the fifth anniversary of the American-led invasion nears, with Senator McCain panning a drawdown proposal offered by Senator Clinton as tantamount to handing victory to Al Qaeda.

The comments from the presumptive Republican nominee, made in a television interview from Baghdad, served as a rebuttal to a speech Mrs. Clinton gave yesterday morning in Washington, during which she took on both Mr. McCain and her remaining Democratic primary rival, Senator Obama, over the war.

The former first lady said Mr. Obama could not be counted on to deliver on his campaign promises to bring American troops home, and that Mr. McCain has tied himself to President Bush’s “failed policy.”

“Senator McCain will gladly accept the torch and stay the course, keeping troops in Iraq for up to 100 years if necessary,” Mrs. Clinton said in a 35-minute address at George Washington University. Messrs. Bush and McCain, she added, “both want to keep us tied to another country’s civil war, a war we cannot win. That in a nutshell is the Bush/McCain Iraq policy. Don’t learn from your mistakes, repeat them.”

Mrs. Clinton repeated her commitment to begin redeploying American troops within 60 days of taking office as president.

In an interview on CNN in Iraq, where he is touring as part of a congressional trip, Mr. McCain characterized Mrs. Clinton’s position as defeatist.

“All I can say is that she obviously does not understand nor appreciate the progress that has been made on the ground,” the Arizona senator said. He added: “So I just think that means Al Qaeda wins.”

The campaign barbs came on a day when Vice President Cheney, in a surprise visit to Iraq, praised the military progress achieved by the president’s “surge” strategy and said the war had been “well worth the effort.” In a study of public opinion polls released yesterday by the American Enterprise Institute, a plurality of Americans — 40% — say the surge is working even as nearly 60% of the country say the war has been a mistake. Polls show that a majority of Americans support a timetable for withdrawal of troops but only 20% back an immediate pull-out.

The fifth anniversary of the beginning of the war falls on Thursday.

Both Democratic candidates have repeatedly seized on Mr. McCain’s suggestion in January that keeping American troops stationed in Iraq for 100 years would be “fine” with him. A spokeswoman for his campaign fired back yesterday, issuing a statement that chastised Mrs. Clinton for taking the senator’s comment out of context. “It is unfortunate that she would look to score political points by mischaracterizing Senator McCain’s statement with intellectually dishonest attacks,” the McCain spokeswoman, Jill Hazelbaker, said.

Mr. McCain was speaking not of a “100-year war,” she said, but of a post-war, non-combat American troop presence similar to those executed in Germany, Japan, and South Korea.

In her speech, Mrs. Clinton said she was adding to her previous Iraq proposals by pledging to remove armed private military contractors and end no-bid contracts; seek an expanded United Nations role in stabilizing Iraq; crack down on the black market for oil, and convene a major diplomatic conference on Iraq early in her presidency that would include Iran and Syria.

She also criticized Mr. Obama, saying that while he gave a speech opposing the war in 2002, he did not follow it up with action in the Senate. “When he had a chance to act on his speech, he chose silence instead,” she said.

Mrs. Clinton pointed repeatedly to a former top foreign policy adviser to the Obama campaign, Samantha Power, who said earlier this month that the Illinois senator would not necessarily rely on his campaign pledges to formulate Iraq policy if conditions on the ground had shifted dramatically by the time he took office. “Giving speeches alone won’t end the war and making campaign promises you might not keep certainly won’t end it,” she said.

Mr. Obama responded by returning to Mrs. Clinton’s 2002 vote to authorize the Iraq war in the first place. “Because of that vote, we are less safe and less respected in the world,” he told reporters in Pennsylvania.

While Mrs. Clinton questioned Mr. Obama’s commitment to withdrawing American troops, her own advisers struggled to articulate how she would respond if her military advisers warned against a pull-out next year. Earlier this month, The New York Sun reported that an architect of the president’s “surge” strategy who has informally advised Mrs. Clinton since she entered the Senate, General Jack Keane, said he had “no doubts” that the senator “would not act irresponsibly and issue orders to conduct an immediate withdrawal from Iraq.”

After persistent questioning by a Washington Post reporter on a conference call, one national security adviser, Lee Feinstein, noted that there are “contingencies” but that Mrs. Clinton was “committed to her plan.” The campaign’s communications director, Howard Wolfson, then answered plainly, “Yes,” to the question of whether Mrs. Clinton would proceed with a withdrawal regardless of the conditions on the ground.