The ad asserts that Mr. Bush is directing the attack on Kerry through a "front" group and is repeating the same tactics he used against Sen. John McCain in the 2000 presidential race, when McCain's Vietnam War record came under attack.
"Bush smeared John McCain four years ago. Now, he's doing it to John Kerry," the announcer in the ad says. "George Bush: Denounce the smear. "Get back to the issues. America deserves better."
The Bush campaign again denied any role in the attacks made by Swift Boat Veterans for Truth, and said the ad's assertion to the contrary was false and libelous.
Separately, former GOP presidential candidate Bob Dole, who was seriously wounded in World War II, joined the battle. Dole said Kerry received an early exit from combat for "superficial wounds."
"One day he's saying that we were shooting civilians, cutting off their ears, cutting off their heads, throwing away his medals or his ribbons," Dole said on CNN's "Late Edition." "The next day he's standing there, 'I want to be president because I'm a Vietnam veteran.' Maybe he should apologize to all the other 2.5 million veterans who served. He wasn't the only one in Vietnam."
Kerry spokesman Chad Clanton replied: "It's unfortunate that Senator Dole is making statements that official U.S. Navy records prove false. This is partisan politics, not the truth."
The dispute over Kerry's war record has taken center stage in the presidential campaign. The New York Times reports that in the days to come, the Kerry campaign hopes to shift the focus from the candidate's Vietnam service to what it claims is a series of dirty tricks carried out by Republicans close to Mr. Bush and his father.
The latest TV ad and a speech Kerry will deliver in New York on Tuesday take this approach, the newspaper said.
Swift Boat Veterans for Truth, a group funded in part by a top GOP donor in Texas, has been running ads featuring veterans who served in Vietnam at the same time as Kerry and question his wartime record.
The group says Kerry didn't deserve his Purple Hearts, lied to get his Bronze Star and Silver Star, wasn't fighting in neutral Cambodia as he said he was and that he unfairly branded all veterans with his 1971 congressional testimony about atrocities in Vietnam.
Initially, Kerry ignored the attacks, but when polls showed his support among veterans to be slipping, the Democrat came out with guns blazing.
At Kerry's urging, a Chicago Tribune editor who commanded one of the swift boats broke his silence, saying Kerry's accounts are accurate, and Kerry's critics' versions are wrong. The man steering Kerry's boat during a key incident also backs Kerry's account.
"The critics have taken pains to say they're not trying to cast doubts on the merit of what others did, but their version of events has splashed doubt on all of us," William Rood said in a 1,700-word first-person account published in Sunday's edition of the Tribune. "It's gotten harder and harder for those of us who were there to listen to accounts we know to be untrue, especially when they come from people who were not there."
Rood said the allegations that Kerry's accomplishments were overblown are untrue and that Kerry came up with an attack strategy that was praised by their superiors. According to the Tribune, Rood's recollection of what happened that day in South Vietnam was backed by military documents.
Kerry also picked up support from Wayne D. Langhofer, who told the Washington Post he was manning a machine gun in a boat behind Kerry's and saw firing from both banks of a river as Kerry dived in to rescue Special Forces soldier James Rassmann, the basis for Kerry's Bronze Star.
Until now, the Post noted on its Web site, Kerry's version of acting under fire had come from crewmen on his own boat. It quoted Langhofer as saying he was approached by leaders of Swift Boat Veterans for Truth several months ago but declined to join them in speaking against Kerry.
Del Sandusky, the pilot of Kerry's boat, tells Newsweek the boat was shaken by a blast, likely from a rocket, knocking Rassmann off the boat.
Kerry was knocked over, hurting his arm. Sandusky says he could see muzzle flashes from the shore and bullets hitting the water.
He says he can't remember if bullets were still flying when Kerry pulled Rassmann out of the river, but in any case, the boat was damaged and taking on water.
According to Newsweek, an official report has a photo showing windows blown out of the swift boat and the engine and steering damaged - although it's unclear when the damage happened.