Jim Cole, Associated Press
Sen. John McCain makes a campaign stop Sunday in Hillsborough, N.H. He criticized other GOP presidential contenders for their biting attacks on Sen. Clinton.

RINDGE, N.H. — Sen. John McCain, R-Ariz., tried Sunday night to make the case that he is best positioned to defeat Sen. Hillary Rodham Clinton, D-N.Y., in a general election, outlining a series of contrasts with her on issues including national security and health care.

In a speech here that his campaign described as the kind of pointed but respectful approach he will take for the rest of the campaign, McCain sought to tap into the anti-Clinton sentiment driving many Republican primary voters, particularly in New Hampshire.

At the same time, he tried to do it in a markedly different way from his two main rivals, Rudolph W. Giuliani and Mitt Romney, who have both harshly attacked Clinton in making their own cases for electability.

The Republicans have taken aim at Clinton early in the campaign, months before even the first votes are cast, making the assumption that her lead position in national polls makes her the likely Democratic nominee. Each is trying to show that he would be best able to run what primary voters assume will be a very rough campaign.

McCain has been struggling to balance his stated desire for a respectful contest with his campaign's recognition that he has a lot of ground to cover in convincing voters that he is the most electable alternative to Clinton. The speech reflected that tension, citing an array of policy differences but using language that was impersonal.

"If I'm your nominee and Sen. Clinton is the nominee of the other party, the country will face as clear a choice as any in recent memory," he told an overflow crowd at Franklin Pierce University. "She will be a formidable candidate. And while our differences are many and profound, I intend this to be a respectful debate. She and I disagree over America's direction, and it is a serious disagreement. But I don't doubt her ability to lead this country where she thinks it should go."

For months, McCain has been rebuffing pressure from some his supporters and aides to step up his criticism of Clinton. But unlike his rivals, McCain has worked closely with Clinton in the Senate and has said repeatedly that he personally likes her.

Still, last week McCain was criticized for not admonishing a questioner at an event in South Carolina who referred to Clinton using a slur. McCain then turned the criticism into a mechanism to raise money for his campaign, resulting in his single biggest day of online fund raising to date.

In his speech on Sunday night, McCain tried to direct the focus of their differences on the question of experience, which he believes will set him apart not just from Clinton but from his Republican rivals.

"There comes a time when a president can no longer rely on briefing books and power points, when the experts and advisors have all weighed in, when the sum total of one's life becomes the foundation from which he or she makes the decisions that determine the course of history," he said. "No other candidate has my experience or the judgment it informs."

McCain, who was a critic of the conduct of the Iraq war but a fierce backer of the surge, said Clinton was inconsistent in her stance.

"Sen. Clinton says we can't abandon Iraq to al-Qaida and the influence of Iran," he said. "On the other, she wants a firm deadline for withdrawal that would do just that."

The McCain campaign points to national polls showing him besting his rivals in head to head match-ups with Clinton, but Sunday's speech was the first time McCain had focused so directly on her.

The setting was no coincidence. A poll last week by the University of New Hampshire of likely Republican primary voters found that 34 percent thought Giuliani had the best chance to defeat the Democratic nominee (Clinton was not named), 30 percent thought Romney was best positioned and 8 percent named McCain.

The campaign must convince voters like Mary Katherine Flanigan, 21, who is deciding between McCain and Giuliani.

"I trust McCain. He has the experience and, you know, he is telling you what he believes," she said after a Saturday night town hall meeting with McCain at Dartmouth. "But I think Rudy may be more electable." She said Giuliani's support of abortion choice makes him more "middle of the road."

When she saw Giuliani a few weeks ago, however, she was surprised both by his close embrace of the Bush administration and his harsh tone, she said.

"I actually didn't like the way he talked about Hillary," she said. Still, she said, she thought it might be effective. "McCain is going to have to get more negative because that is the nature of politics."

McCain said he knows attacking Clinton is an easy way to stir voters, but he disapproved of the tactics employed by Romney and Giuliani.

"I don't think you should take shots at her, like imitating her voice," McCain said during a discussion on his bus, referring to a routine Giuliani has used at campaign appearances. "I don't know what you gain by doing that. I guess issuing inflammatory statements can be effective. But I can't campaign that way."

"If they think indulging in personal attacks and disparaging people's character is the way to get the nomination and win an election, I am not their guy," McCain said on his bus. "I have never attacked people personally, and I am sure as hell not at the age now where I am going to start."

McCain, when asked why Clinton inspires such a visceral reaction among conservatives, said it was fueled by a media environment that thrives on clashes between extremes.

"I surmise that it has to do with the whole Clinton era. The impeachment. That she is associated with all of the very inflamed passions of that period of time," he said. "I don't know how else to explain it."

After the speech, McCain fielded questions from the crowd and a young man rose to praise McCain. But he added he was concerned about whether McCain was a strong enough campaigner to beat Clinton, contrasting him with Giuliani, who he said impressed him as "tough."

"Do you think you can really be tough enough on Sen. Clinton to win the general election?" the young man asked.

McCain said that one needed to look no further than his standing up and speaking out when he saw the strategy in Iraq going terribly wrong while Giuliani remained silent because he did not have the experience and background to understand the situation.

As to his reticence to attack Clinton with the same relish as Giuliani, McCain said, "You can be tough but you should never degrade or ridicule anyone who is seeking public office. But we see too much of it."