Democrat John Kerry's (search) campaign says "George Bush is up to his old tricks" in a new television ad that shows GOP maverick John McCain (search) telling Bush in 2000 "you should be ashamed" for standing by as a "fringe veterans group" questioned his patriotism.

"Four years ago it was John McCain," the ad says. "This year, they're smearing John Kerry. George Bush, denounce the smear. Get back to the issues."

The 60-second ad is the Kerry campaign's third commercial responding to ads by Swift Boat Veterans for Truth (search), which ran an ad accusing Kerry of lying about his war record.

Bush has criticized all ads by outside groups, but Democrats argue that Bush didn't specifically condemn the swift-boat veterans' ad.

Kerry and running mate John Edwards, who was campaigning in Ohio on Wednesday, have accused Bush of being behind the group's "lies and smears," and Democrats have compared the attacks to those on McCain during the 2000 Republican primaries. Bush's campaign has denied being behind the swift-boat group, whose major financial backer is a Texas Republican with ties to Bush aides.

McCain, who supports Bush, has condemned the anti-Kerry ad, calling it "dishonest" and "dishonorable."

The new ad from the Kerry campaign features McCain saying, "Let me tell you what really went over the line," during a debate in February 2000.

Sitting next to Bush, the former prisoner of war says that when "a fringe veterans group" attacked him at a Bush campaign function, Bush stood by and didn't say a word. "That fringe veteran said that John McCain had abandoned the veterans. Now I don't know how if you can understand this, George, but that really hurts," McCain says, adding that five U.S. senators wrote Bush a letter and said "apologize."

"You should," McCain says. "You should be ashamed."

The same clip was used for a Web video the Kerry campaign sent to supporters on Saturday.

Kerry's campaign is spending a small amount — about $250,000 over a week — to run the ad in Nevada, New Mexico and Pennsylvania, as well as on a national cable network, to counter a spot the swift-boat group is running in the three states. It criticizes Kerry's anti-war activities upon his return from Vietnam.

On Wednesday, the swift-boat group poured more money into the three states, meaning it will spend nearly $700,000 to run its ad for a week.