Former GOP gubernatorial nominee Ovide Lamontagne is filing today to run for Senate in New Hampshire, adding to an already crowded GOP primary in the Granite State.

"I believe that I can build a coalition that not only can win in the primary but in the general election," Lamontagne said in a Monday phone interview.

Lamontagne has been exploring a bid for the last couple months, headlining events in both Washington, D.C. and New Hampshire.

Businessman Sean Mahoney, a national committeeman for the RNC, confirmed Monday in an interview with UnionLeader.com that he is actively exploring a bid to represent New Hampshire in the U.S. Senate.

Mahoney's potential candidacy is the latest possible complication for former New Hampshire Attorney General Kelly Ayotte, who has been boosted by the National Republican Senatorial Committee for the U.S. Senate, though the committee has stopped short of an official endorsement. Ayotte is officially in the exploratory stage. Republican Ovide Lamontagne, an attorney who ran for governor in 1996, is also exploring a U.S. Senate candidacy.

The party is fighting to hold the seat currently represented by Republican Sen. Judd Gregg, who is retiring.

New Hampshire's state Democratic party released a web ad Wednesday comparing Republican state Attorney General Kelly Ayotte to Alaska Republican Gov. Sarah Palin.

Ayotte on Tuesday announced her resignation as Attorney General to explore a bid for U.S. Senate. Palin on July 3 announced her resignation as governor and has left the door open to future political endeavors, including a presidential campaign in 2012.

Palin received harsh blowback from some colleagues for leaving office mid-session.

Former New Hampshire Gov. John H. Sununu, the current Republican state party chairman, told the Portsmouth Herald during an editorial board meeting earlier this week that his son, former U.S. Sen. John E. Sununu, will soon decide whether to enter the 2010 Senate race.

And the elder Sununu, a former governor, added that he expects the GOP field to clear for his progeny.

"I will use my warmth and my charm to make sure that if it is a primary, there is a constructive primary or if a primary can be avoided, I will do that," Sununu said. When asked if he would prefer to avoid a primary between his son and Republican state Attorney General Kelly Ayotte, he responded: "I think if my son runs, there will not be a primary."