WASHINGTON (AP) — Colin Powell, a Republican who was President Bush’s first secretary of state, endorsed Democrat Barack Obama for president Sunday and criticized the tone of Republican John McCain’s campaign.

Powell said both Obama and Republican John McCain are qualified to be commander in chief. But he said Obama is better suited to handle the nation’s economic problems as well as help improve its standing in the world.

“It isn’t easy for me to disappoint Sen. McCain in the way that I have this morning, and I regret that,” Powell, interviewed on NBC’s “Meet the Press,” said of his longtime friend, the Arizona senator.

“But I firmly believe that at this point in America’s history, we need a president that will not just continue, even with a new face and with the changes and with some maverick aspects, who will not just continue basically the policies that we have been following in recent years,” Powell said.

“I think we need a transformational figure. I think we need a president who is a generational change and that’s why I’m supporting Barack Obama, not out of any lack of respect or admiration for Sen. John McCain.”

Powell’s endorsement has been much anticipated because he is a Republican with impressive foreign policy credentials, a subject on which Obama is weak. At the same time, he is a black man and Obama would be the nation’s first black president.

Powell said he was cognizant of the racial aspect of his endorsement, but said that was not the dominant factor in his decision. If it was, he said, he would have made the endorsement months ago.

Powell also expressed disappointment in the negative tone of McCain’s campaign, his choice of Alaska Gov. Sarah Palin as a running mate and McCain’s and Palin’s decision to focus in the closing weeks of the contest on Obama’s ties to 1960s-era radical William Ayers.

He said McCain’s choice of Palin raised questions about judgment.

“I don’t believe she’s ready to be president of the United States,” Powell said.

Powell, as secretary of state, helped make the case before the United Nations for the U.S.-led invasion of Iraq, launched in March 2003. A retired general, he also was the nation’s top military commander, chairman of the Joint Chiefs of Staff, during the first Gulf war under President George H.W. Bush.

McCain disagreed with Powell’s decision and said he has been endorsed by four other former secretaries of state, all veterans of Republican administrations: Henry Kissinger, James A. Baker III, Lawrence Eagleburger and Alexander Haig.

“Well, I’ve always admired and respected Gen. Powell. We’re longtime friends. This doesn’t come as a surprise,” McCain said on “Fox News Sunday.”

Asked whether Powell’s endorsement would undercut his campaign’s assertion that Obama is not ready to lead, McCain said: “Well, again, we have a very, we have a respectful disagreement, and I think the American people will pay close attention to our message for the future and keeping America secure.”

Powell said he does not plan to campaign for Obama.