Republican Rudy Giuliani says he will try to follow former President Ronald Reagan's lead and stay out of the latest dustup between presidential candidates.

"Everybody wants the nomination. You point out the things that are most important to you," he told reporters Sunday. ... (Reagan) used to have an 11th commandment, that was thou shall not attack another Republican.

"I'm going to try to follow that commandment as much as I can," Giuliani said.

On Friday, Mitt Romney told an audience in Nevada that he is the most credible Republican seeking the party's presidential nomination. A day later, John McCain scoffed at the assertion and recalled Romney's moderate politics and past support of Democratic candidates.

Giuliani seemed content to let them have at it. But he was quick to point out what he suggested where inconsistencies in the records of both candidates.

"Honestly, I have the only results. I'm the only one who reduced taxes," Giuliani said, repeating a shot at Romney's record as Massachusetts governor.

He also touted his support for President George W. Bush's tax cuts, which McCain initially opposed.

Giuliani said Republican voters will decide who is the best candidate.

"Every four years, we let the Republican Party members decide who they think can be the best representative of the party, who we think can be the strong fiscal conservative, who we think can defend the country the best, who represents their values the most. Let the party decide that," Giuliani said after greeting voters at a restaurant.

He then turned to a key argument for his campaign: that he is the only Republican in the race who can defeat Sen. Hillary Rodham Clinton, the Democratic front-runner.

"And let's make sure we pick someone who can beat the Democrats. That's what it's all about," Giuliani said. "We have our differences, but they're small. Us Republicans have differences between and among ourselves. But they're small compared to the vast differences we have with the Democrats."

Later Sunday, during a town-hall meeting in Exeter, New Hampshire, Giuliani assured a young questioner that preparedness will be key for all crises, including those from outer space.

"If (there's) something living on another planet and it's bad and it comes over here, what would you do?" a boy asked.

Giuliani, grinning, said it was his first question about an intergalactic attack.

"Of all the things that can happen in this world, we'll be prepared for that, yes we will. We'll be prepared for anything that happens," said Giuliani, who was mayor of New York City during the Sept. 11, 2001, terrorist attacks.