Rail.

That may be the first word voters think of when they’re evaluating former Gov. Ben Cayetano‘s candidacy for Honolulu mayor. But in announcing his run Thursday at a motorcycle shop off of the H-1 freeway, Cayetano made a point of not leading with his opposition to the project.

He waited 10 minutes before even mentioning the word in his opening speech. After first introducing and thanking the many family and friends that packed the second-floor conference room, he criticized the “reckless spending” at Honolulu Hale and said a series of politicians have failed to give proper attention to the aging sewer and water systems and the city’s roads over “three decades of neglect.”

“My opponents are going to try to say, ‘Ben Cayetano is a one-issue candidate,'” he said. “They are the one-issue candidates. All Carlisle thinks about is rail. All Caldwell thinks about is rail.”

Cayetano — with help from Cabinet-level advisors to former Mayors Jeremy Harris and Frank Fasi as well as current Honolulu City Council members Ann Kobayashi and Romy Cachola — promised to unveil a plan next week that addresses the costs of repairing and upgrading the city’s sewer and water systems.

“If there is one issue in his head, it’s money. It’s the proper allocation of money by the city government. That has not been done,” one of Cayetano’s co-chairs, retired Judge Walter Heen, told Civil Beat after the press conference.

But despite the protestations, opposition to the Honolulu rail project is undoubtedly the bedrock of Cayetano’s new campaign. He’s still a plaintiff in the federal lawsuit seeking to stop rail, as is Heen. When he introduced Heen, he jokingly referred to him as part of “this gang,” a reference to rail proponents’ term of Cayetano, Heen, Cliff Slater and Randy Roth as “the gang of four.”

Cayetano criticized the Honolulu Authority for Rapid Transportation for awarding rail construction contracts before getting a commitment of federal funds for the project. He criticized Mayor Peter Carlisle for promising to “plow forward” with rail, and criticized Kirk Caldwell, the other candidate in the race, for his support for rail transit.

Caldwell held his own press conference at the future site of a Joint Traffic Management Center on King Street about an hour after Cayetano’s wrapped up. He shot back that Cayetano had previously offered Caldwell his support against Carlisle and wasn’t even his own first choice for mayor.

“He wants to be fully engaged in a fight, and I do think that Ben in large part is running because of rail,” Caldwell said. “I think he is frustrated by the lawsuit that he brought, and it’s not moving fast enough … and so he’s going to take it to another level by running. And it is about one issue to him. It is about rail.”

In a written statement, Carlisle Campaign Manager Cha Thompson said, “Rail will not bankrupt the city. It’s an investment in the next generation, offering commuters a quality of life choice in dealing with traffic misery. Mayor Peter Carlisle is committed to bringing fiscal discipline to the city. He will grow our economy by continued investments in sewer upgrades, road repairs and other infrastructure projects.”

Cayetano’s entry instantly turns the race into one of the biggest on Hawaii’s ballot in 2012.

The other headliner involves another former governor. Linda Lingle, Cayetano’s one-time opponent and eventual successor at Washington Place, is running for a vacant U.S. Senate seat.

Cayetano, now 72 years old, has a long history of electoral success. He was twice lieutenant governor under John Waihee and a two-term governor from 1994 until 2002.

Cayetano’s announcement is in many ways the culmination of rail opponents’ three-pronged attack on the project. There’s the lawsuit, which argues that rail planners didn’t adequately consider alternatives. If it prevails, it would effectively halt the project. There’s the public relations arm, writing op-eds and holding town halls, seeking to undermine support for the project. And now there’s the political or the electoral arm, which will give rail skeptics an option at the ballot box for the third straight election.

In 2008, voters narrowly approved a Charter amendment approving steel-on-steel rail by a vote of 51-47. In 2010, they approved a second Charter amendment, this time creating an independent authority to oversee rail construction and operations.

In both years, they had Panos Prevedouros as a mayoral option. The University of Hawaii engineering professor was a one-note candidate, earning about 20 percent of the vote solely on the basis of his opposition to rail.

But Prevedouros is not running in 2012, and quickly pledged his help in an email distributed to supporters. Another potential anti-rail candidate, Sen. Clayton Hee, stood next to Cayetano at the press conference with a large grin on his face.

Assuming Cayetano is able to attract all of the anti-rail voters that had gone for Prevedouros and is able to turn out the Filipino vote — Filipinos are now the largest Asian ancestry group in Hawaii, recently surpassing Japanese — that alone might give Cayetano enough votes to advance from the all-entrants-welcome Aug. 11 primary to a mano-a-mano run-off in the Nov. 6 general election.

It might even be enough to make him the front-runner, though pro-rail or union voters split between Carlisle and Caldwell in the primary might coalesce around whoever survives.

With three well-known candidates on the ballot, it will be difficult for anyone to secure more than half of the vote in the primary, the threshold needed to avoid a general election run-off.