For a second day, McCain criticized Obama for saying, in a debate last year, that as president he would meet with the leaders of Cuba, Iran and Venezuela without preconditions.

McCain insisted such a meeting could endanger national security, sounding a theme that is likely to persist until the November general election.

The Arizona senator recalled the ridicule President Jimmy Carter faced in 1979 when he kissed Soviet leader Leonid Brezhnev during the signing of an arms treaty.

"Carter went over and kissed Brezhnev, remember?" McCain said yesterday in Miami. "So it's dangerous. It's dangerous to American national security if you sit down and give respect and prestige to leaders of countries that are bent on your destruction or the destruction of other countries. I won't do it, my friends."

Obama protested that McCain was distorting his position and said he would try to lay ground rules for such a meeting. "John McCain likes to characterize this as me immediately having Raul Castro over for tea," he said on CNN. "What I've said is that we would set a series of meetings with low-level diplomats, set up some preparation, but that over time, I would be willing to meet and talk very directly about what we expect from the Cuban regime."

In July, Obama answered unequivocally, "I would," to the question of whether he would meet, without precondition, with leaders of Iran, Syria, Venezuela, Cuba and North Korea.

On Monday, McCain raised the specter of a President Obama meeting with Iranian President Mahmoud Ahmadinejad. He said Obama displayed inexperience and reckless judgment in his willingness to talk with a sponsor of terrorism.

Although Obama himself has not previously disputed assertions that he meant he would meet with Ahmadinejad, the Illinois senator yesterday told CNN he did not necessarily mean he would meet with Ahmadinejad himself.

Yesterday, dozens of people at McCain's town-hall-style forum in Miami booed as he raised the notion of a meeting with Castro, and they gave McCain a standing ovation when he said that, as president, he would pressure Castro to release political prisoners unconditionally, schedule internationally monitored elections, and legalize political parties, unions and free media.

McCain also criticized Obama for shifting his stance on the trade embargo against Cuba; Obama said in 2003 he would lift it but more recently has said he would ease it. McCain argues that trade should not be normalized until the basic freedoms he outlined are granted.

Obama and Democratic rival Hillary Rodham Clinton are scheduled to campaign today in Florida.