Former Massachusetts Sen. Scott Brown (R) is officially in the race to unseat Sen. Jeanne ShaheenCynthia (Jeanne) Jeanne ShaheenKoch-backed group launches 7-figure ad blitz opposing .5T bill Senate lawmakers let frustration show with Blinken We have a plan that prioritizes Afghanistan's women — we're just not using it MORE (D-N.H.), he announced Thursday evening, after flirting with a bid for months.


"Starting today, I am a candidate for the United States Senate for the state of New Hampshire," Brown told supporters at a rally in Portsmouth, N.H.

The former Massachusetts senator touted his connections to the state, mentioning that he was born there, before attacking Shaheen for backing ObamaCare.

"She is very a nice person, but she's wrong on the issues facing the people of New Hampshire. She made that clear when she cast the deciding vote to pass ObamaCare," he said, later joking that the healthcare reform law makes New Hampshire voters "live free or log on."

Brown ripped the "out of step, out of touch Obama-Shaheen agenda" and promised to be "nobody's yes man," talking up New Hampshire's independent streak.

Brown's bid gives Republicans a chance in the swing state despite Shaheen's personal like-ability, and helps the GOP expand the Senate map.

Shaheen's campaign fired back, attacking Brown as a carpet-bagger beholden to his donors.

"If Scott Brown gets through the Republican primary, this election will be a choice between someone who cares only about himself and the big corporate interests that fund his campaign and someone who works every day to make a difference for New Hampshire families. New Hampshire voters know Jeanne Shaheen shares their values," Shaheen campaign manager Mike Vlacich said in a statement.

He's been on a weeks-long listening tour across the state, following a move to New Hampshire last year after his loss to Sen. Elizabeth Warren (D-Mass.). He'll have to get past carpet-bagging charges, however, as well as recent comments that he might not be the most qualified to represent New Hampshire in the Senate.

"Do I have the best credentials? Probably not. 'Cause, you know, whatever. But I have long and strong ties to this state," he told The Associated Press in late March.

A new poll released Thursday evening found Shaheen up, but the race was tightening. Shaheen leads Brown by 45 percent to 39 percent in the WMUR/University of New Hampshire poll. 

He's the presumptive GOP front-runner, though a number of other Republicans, including former Sen. Bob Smith (R-N.H.), are also in the race.

Brown made sure to plug his iconic red truck in the speech.

"I'm pretty proud of that old GMC Canyon. It's got close to 300,000 miles on the odometer, and it’s sure looking good with those license plates that say, 'Live Free or Die,' " he said.