Los Angeles ? President Bush declined Thursday night to denounce a television ad blistering the military service record of his Democratic rival, John Kerry.

“I haven’t seen the ad,” Bush said, instead condemning the proliferation of independent groups mounting their own political advertising campaigns.

“They’ve said some bad things about me. I guess they’re saying bad things about him,” Bush told CNN’s Larry King during an hourlong interview. “What I think we ought to do is not have them on the air.”

The 60-second spot that has drawn stinging criticism from Sen. John McCain, R-Ariz., among others, is being aired by Swift Boat Veterans for Truth. It is a so-called “527” group, which, under that section of the tax code, can raise unlimited funds for independent political expenditures.

The ad accuses the Massachusetts senator, a decorated Vietnam veteran, of lying about his service record and later betraying fellow veterans by opposing the war.

McCain, a Navy flier held prisoner in Vietnam who campaigned with Bush two days this week, has called the commercial “dishonest and dishonorable” and urged the White House to speak out against it.

White House press secretary Scott McClellan, like the president, has declined to condemn it, while saluting Kerry’s service as honorable.

The Kerry campaign, in a forceful response, took after the president Thursday.

“Once again, the president side-stepped responsibility and refused to do the right thing,” campaign spokesman Chad Clanton said.

Talk show host Larry King, right, listens to President Bush, left, and his wife, Laura Bush, during an interview during a taping of Thursday's Larry

The president and first lady Laura Bush sat down with King at a campaign stop in California.

Earlier, Bush campaigned in a union hall in Las Vegas and paid visit to Nancy Reagan, just after arriving in Los Angeles.

“She’s very strong,” Bush told King. “She is recovering from a painful period in her life when she lost the love of her life, a great president, Ronald Reagan.”

Reagan thanked Bush for his courtesies and, in a written statement, fully embraced his candidacy for re-election.

She and her son, Ron, who addressed the Democratic convention last month, differ with Bush’s decision to limit federal funding for stem cell research to 78 embryonic stem cell lines. But McClellan said the issue never arose Thursday.

In Las Vegas, Bush continued to paint Kerry as an unprincipled, wavering senator, accusing him of trying to turn a White House decision to store nuclear waste at Yucca Mountain into a “political poker chip.”