A new tongue-in-cheek ad from John McCain's Senate campaign has the Arizona lawmaker's leading Republican primary opponent, J.D. Hayworth, declaring that President Barack Obama was born in Kenya, believing that vampires are real and preparing for an alien invasion.

"I'm J.D. Hayworth and I'm running for US Senate to take on the pressing challenges facing Arizona, America and indeed the entire human race," the ad -- paid for by McCain's campaign -- begins.

"First, I've committed to exposing the secret Kenyan birthplace of the president of the United States," the fake "Hayworth" declares as footage from Disney's The Lion King rolls on the video. "Second, I've stood up against the grave threat of man-horse marriage. Third, I believe that Dracula is real."

The ad concludes with "Hayworth" declaring that he is preparing to tackle "our most critical national security threat" as footage of the alien-invasion movie Mars Attacks rolls on screen.

Much of the ad mocks the less-than-flattering media attention Hayworth, a former GOP House member and conservative talk show host in Phoenix, has received in recent weeks.

Last month he drew criticism when he told an Orlando radio station that Massachusetts' law allowing gay marriage "would mean if you really had affection for your horse, I guess you could marry your horse."

Hayworth, who is trailing McCain in the polls but is considered the favored candidate among Tea Party Republicans, appeared on MSNBC in January and demanded that the president should "come forward" with his birth certificate, a move that had him labeled as being firmly in the "birther" camp.

But it was a joke by a former Arizona attorney general that got Hayworth labeled, fairly or otherwise, as a believer in vampires.

"Someone needs to drive a wooden stake through [Hayworth's] heart," joked Grant Woods in a recent Newsweek interview.

"This cavalier death threat that he issued is over the top," Hayworth responded, adding that making a "death threat" in a national magazine is "beyond the pale."

"No, J.D., unless you are in fact a vampire, interpreting an innocent reference to pop-culture as a death threat is what's 'beyond the pale,'" quipped blogger James King at the Phoenix New Times.

In the latest poll, McCain is solidly leading Hayworth by a margin of 15 percentage points. But news analysts suggest the longtime senator, known for being a moderate, is taking the threat from Tea Party challengers seriously, which may explain his recent reversals on some issues.

Most recently, McCain declared he had "never considered" himself a "maverick" -- this despite the fact the word was practically the senator's catch-phrase when he ran for president in 2008.

"Considering just how quickly McCain himself has dropped pretenses of political moderation (denying, for example, that he every called himself a maverick), it takes a certain amount of chutzpah for him to accuse his opponent of lacking seriousness," writes Sam Stein at the Huffington Post.

"But Hayworth has made the case easy -- certainly with his dabbling in birther conspiracies. And in the process, he's demonstrating just how hard it is to walk the line between Tea Party activism and sensible conservatism."

The following video was uploaded to YouTube by John McCain's campaign, April 12, 2010.