BLUFFTON, S.C. -- Republican presidential candidate John McCain said Monday the war in Iraq has been mismanaged for years and former Defense Secretary Donald Rumsfeld will be remembered as one of the worst in history.

"We are paying a very heavy price for the mismanagement _ that's the kindest word I can give you _ of Donald Rumsfeld, of this war," the Arizona senator told an overflow crowd of more than 800 at a retirement community near Hilton Head Island, S.C. "The price is very, very heavy and I regret it enormously."

McCain, the ranking Republican on the Senate Armed Services Committee, complained that Rumsfeld never put enough troops on the ground to succeed in Iraq.

"I think that Donald Rumsfeld will go down in history as one of the worst secretaries of defense in history," McCain said to applause.

The comments were in sharp contrast to McCain's statement when Rumsfeld resigned in November, and failed to address the reality that President Bush is the commander in chief.

"While Secretary Rumsfeld and I have had our differences, he deserves Americans' respect and gratitude for his many years of public service," McCain said last year when Rumsfeld stepped down.

On a two-day campaign swing in South Carolina, McCain fielded questions from the crowd for more than an hour and said the United States can succeed in Iraq with additional troops and a new strategy. McCain has been a strong proponent of using more troops and favors Bush's increase of some 21,500 U.S. forces in the nearly four-year-old war.

"I have been saying for 3 1/2 years that we would be in this sad situation and this critical situation we are in today," he said.

McCain's bid for president was sidetracked in South Carolina in 2000 after a victory in New Hampshire. George W. Bush won the primary here and went on to win the nomination and White House.

"In life, one of the worst things you can do is hold a grudge," he said. "I felt the important thing for me to do with my life was to move forward after we lost our race. You have seen other people who have lost who mire themselves in bitterness and self pity. That's not what my life is all about."

Some in the crowd were Bush supporters who have not yet decided on a 2008 candidate.

"It's too early to say," said Paul Baker, a retiree from Niagara Falls, N.Y., who has lived in South Carolina about four years. "I'm just going to wait it out and see what happens."