LAS VEGAS—Scott Ashjian is one of those Vegas characters.

He wears a platinum Rolex and slicks his hair back, Mad Men-style. He got his start in car washes, went into asphalt and now has a company that floods the Internet with flattering information about people worried they look bad in Google searches. He keeps a Playboy-themed pinball machine in his office, drives a $160,000 black Mercedes with a night-vision system, and carries a pistol under his suit jacket.

And he just might be the man who determines the outcome of the highest-profile Senate race in the country.

Scott Ashjian, U.S. Senate candidate of the Tea Party of Nevada, in his Las Vegas office Wednesday. Others claiming the tea-party mantle are suing to have him ousted from the ballot. Tiffany Brown for the Wall Street Journal

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So volatile is the mood of the electorate, and so strong the anti-establishment anger, that Mr. Ashjian—a political unknown who barely bothers to campaign—may well tip the scales in favor of beleaguered Senate Majority Leader Harry Reid, a Democrat, in his race with Republican challenger Sharron Angle.

Why? Ms. Angle, a former state assemblywoman, may be the standard-bearer for the tea-party faithful, but Mr. Ashjian alone will have the words "tea party" next to his name on the ballot. While others were staging angry rallies, Mr. Ashjian registered as the Senate candidate of the Tea Party of Nevada, which he formed with his podiatrist, his bankruptcy lawyer and a few other friends.

The Vegas-style theatrics highlight a serious quandary of the diffuse tea-party movement: Who's to say just who is—and is not—an authentic tea partier?

Republican operatives and other self-identified tea partiers have filed two lawsuits attempting to force Mr. Ashjian and his organization from the ballot. Mr. Ashjian wrote to Ms. Angle demanding that she cease claiming to be the "tea-party candidate" and otherwise infringing on "my rights as the only authorized 'Tea Party Candidate of Nevada.' "

"Anybody can more or less say they're part of the tea-party movement," says the plaintiff in one anti-Ashjian lawsuit, Tim Fasano, a self-described tea partier in Nevada running for Senate for the Independent American Party.

Mr. Ashjian's candidacy has heartened Democrats and panicked Republicans, who fear he will siphon conservative votes from Ms. Angle. The latest CNN/Time poll of likely voters has Mr. Reid and Ms. Angle in a statistical tie, 41% to 42%, with Mr. Ashjian drawing 5%.

The two lawsuits claim he should be disqualified from the ballot for alleged technical violations. Behind the details, however, is the feeling that Mr. Ashjian hasn't tea-partied enough to be a tea partier.

"The guy is a huckster, he's a slimeball," says former Nevada GOP Executive Director Chuck Muth, co-plaintiff in one suit.

Family Feud

Fights have broken out around the U.S. over who represents the tea-party movement.

Florida:Republican Don Hensarling of the 912 Project tea-party group sues to oust Florida TEA Party candidate Peg Dunmire from the ballot.

Doug Hoffman Associated Press

New York:Upstate New York Tea Party urges Conservative Party candidate Doug Hoffman to exit a House race, fearing he will help the Democrat defeat a conservative Republican.

Peter DeStefano Associated Press

New Jersey: Peter DeStefano (left) has alarmed Republicans and self-declared teapartiers by registering for a House race as the New Jersey Tea Party candidate.

Michigan: Two tea-party conservatives appear likely to split the vote for an open House seat.

Mr. Ashjian, 46 years old, says he attended a few tea-party protests. "Do I show up at every barbecue? The Tea Party of Nevada is a revolt against big government," he says.

So far, the courts have sided with Mr. Ashjian, and both cases are now on the docket of the state Supreme Court.

Mr. Ashjian's paternal great-grandfather, an Armenian Christian, emigrated to the U.S. in the early 20th Century and wound up a wealthy grape farmer in California.

After high school, Mr. Ashjian turned down a wrestling scholarship and instead started a car wash in Bakersfield, Calif. "There's no money in wrestling," he explains.

He visited Las Vegas in 1994 to watch a boxing match and decided that the gambling mecca was the land of opportunity. Inspired by a customer who had a paving company and drove a Cadillac, Mr. Ashjian launched A&A Asphalt Paving Co. in Las Vegas, the first of a string of Ashjian companies that have gone into and out of business, according to state records. In March, the state Contractors Board cited Mr. Ashjian for failing to pay a supplier and revoked A&A's license.

Mr. Ashjian says it was a routine billing dispute, and that the company fell victim to the local construction slump. "Even if you fail in your business and you come back—that's what makes a good businessman," says attorney Barry Levinson, who handled the reorganization of a bankrupt Ashjian mini-storage project.

Mr. Ashjian won't say who suggested that he run for the Senate, except that it wasn't a Democrat. When he formed the Tea Party of Nevada in January, he made his podiatrist its chairman and Mr. Levinson its secretary.

Neither major campaign is eager to talk about Mr. Ashjian. The Reid camp knows it gains by quietly letting Mr. Ashjian nibble at Ms. Angle's conservative support. Ms. Angle appears content to let surrogates try to fend off Mr. Ashjian. They allege that he is a stalking horse for Mr. Reid, but present no evidence.

Mr. Ashjian says his concerns are tea-party staples: lower taxes; smaller government; and business-friendly regulation.

Yet his is an odd campaign. He doesn't give speeches or hold rallies. He doesn't knock on doors or buy TV time. Mr. Ashjian says he has raised about $5,000 from donors and paid for the rest himself.

He is, he admits, counting on angry Nevadans to check the box next to the man identified as the Tea Party candidate. Mr. Reid and Ms. Angle "are spending tens of millions of dollars going after each other, and we're just sitting back and going up in the polls," Mr. Ashjian says.

He thinks the lawsuits and anger are just proof that he is shaking up the new anti-establishment establishment.

Behind his desk, Mr. Ashjian keeps a statue of a kingfisher about to lunge at a frog. "That's Sharron Angle," Mr. Ashjian says of the frog. "That's Harry Reid," he says of the bird. Lurking beneath a lily pad, eyes just above the water's surface, is an alligator, ready to devour both.

"That's Scott Ashjian," he says with a crocodilian smile.