LAKEVILLE, Minn. – The anger is getting raw at Republican rallies and John McCain is acting to tamp it down.

McCain was booed by his own supporters Friday when, in an abrupt switch from raising questions about Barack Obama's character, he described the Democrat as a “decent person and a person that you do not have to be scared of as president of the United States.”

A sense of grievance spilling into rage has gripped some GOP events this week as McCain supporters see his presidential campaign lag against Obama. Some in the audience are making it personal, against the Democrat. Shouts of “traitor,” “terrorist,” “treason,” “liar,” and even “off with his head” have rung from the crowd at McCain and Sarah Palin rallies, and gone unchallenged by them.

McCain changed his tone Friday when supporters at a town hall pressed him to be rougher on Obama. A voter said, “The people here in Minnesota want to see a real fight.” Another said Obama would lead the U.S. into socialism. Another said he did not want his unborn child raised in a country led by Obama.

“If you want a fight, we will fight,” McCain said. “But we will be respectful. I admire Sen. Obama and his accomplishments.” When people booed, he cut them off.

“I don't mean that has to reduce your ferocity,” he said. “I just mean to say you have to be respectful.”

Presidential candidates are accustomed to raucous rallies this close to Election Day and welcome the enthusiasm. But they are also traditionally monitors of sorts from the stage. Part of their job is to leaven proceedings if tempers run ragged and to rein in an out-of-bounds comment from the crowd.

Not so much this week, at GOP rallies in Pennsylvania, Wisconsin, Florida and other states.

When a visibly angry McCain supporter in Waukesha, Wis., on Thursday told the candidate “I'm really mad” because of “socialists taking over the country,” McCain stoked the sentiment. “I think I got the message,” he said. “The gentleman is right.” He went on to talk about Democrats in control of Congress.

On Friday, McCain rejected the bait.

“I don't trust Obama,” a woman said. “I have read about him. He's an Arab.”

McCain shook his head in disagreement, and said:

“No, ma'am. He's a decent, family man, citizenthat I just happen to have disagreements with (him) on fundamental issues and that's what this campaign is all about.”

He had drawn boos with his comment: “I have to tell you, he is a decent person and a person that you do not have to be scared of as president of the United States.”

The anti-Obama taunts and jeers are noticeably louder when McCain appears with Palin, a big draw for GOP social conservatives. She accused Obama this week of “palling around with terrorists” because of his past, loose association with a 1960s radical. If less directly, McCain, too, has sought to exploit Obama's Chicago neighborhood ties to William Ayers, while trying simultaneously to steer voters' attention to his plans for the financial crisis.

The Alaska governor did not campaign with McCain on Friday, and his rally in La Crosse, Wis., earlier Friday was much more subdued than those when the two campaigned together. Still, one woman shouted “traitor” when McCain told voters Obama would raise their taxes.

Volunteers worked up chants from the crowd of “U.S.A.” and “John McCain, John McCain,” in an apparent attempt to drown out boos and other displays of negative energy.

The Secret Service confirmed Friday that it had investigated an episode reported in The Washington Post in which someone in Palin's crowd in Clearwater, Fla., shouted “kill him,” on Monday, meaning Obama. There was “no indication that there was anything directed at Obama,” Secret Service spokesman Eric Zahren told AP. “We looked into it because we always operate in an atmosphere of an abundance of caution.”

Palin, at a fundraiser in Ohio on Friday, told supporters “it's not negative and it's not mean-spirited” to scrutinize Obama's iffy associations.

But Kathleen Hall Jamieson, director of the Annenberg Public Policy Center at the University of Pennsylvania an author of 15 books on politics, says the vitriol has been encouraged by inflammatory words from the stage.

“Red-meat rhetoric elicits emotional responses in those already disposed by ads using words such as 'dangerous' 'dishonorable' and 'risky' to believe that the country would be endangered by election of the opposing candidate,” she said.

Beth Fouhy reported from New York. Associated Press writer Joe Milicia contributed to this story from Cleveland.