But Tuesday night Scott Brown became the Republican nominee for Senate in New Hampshire and will now face the incumbent, Democrat Jeanne Shaheen, in what has already become a competitive and bitterly contested race that has drawn millions of dollars in attack ads from outside groups.

CONCORD, N.H. — It would have been a bizarre fantasy five years ago, when he was a little-known state senator from Wrentham. And it would have been hard to fathom two years ago, when he was a US senator from Massachusetts.

Brown comfortably dispatched several party rivals, including his two most serious opponents, former state senator Jim Rubens and former US senator Bob Smith, according to the Associated Press.


Brown and Shaheen, who did not face a challenge for the Democratic nomination, are expected to continue running campaigns with starkly divergent themes: the challenger speaking about national issues, the incumbent sticking to local accomplishments. Aides to both say they don't expect that messaging to substantially change in the general election race.

Brown is focusing on retail political events, meeting voters while discussing federal issues — from immigration to the growing threat from the Islamic State of Iraq and Syria — and trumpeting his independence. He paints his opponent as painfully partisan, and he rarely misses an opportunity to note that she votes in lockstep with President Obama, who polls have found is increasingly unpopular in the Granite State.

Shaheen is relentlessly focused on the town-by-town, city-by-city specifics of what she has done for New Hampshire, while framing the former Massachusetts senator as driven by self-interest and woefully out of touch with his new home state. (Brown moved his primary residence to New Hampshire last year.)

With 75.7 percent of precincts reporting Tuesday night, Brown led with 49.9 percent of the vote, according to the Associated Press. Rubens, his next closest rival, had 23.7 percent.


In Manchester Tuesday, Shaheen addressed a crowd of about 500 supporters for 10 minutes. Her remarks were sharp and pointed in the direction of Brown.

"No matter where he lives, Scott Brown will not be there for working people," said Shaheen, ticking off a list of Brown's financial ties to Wall Street and business alliances she says have hurt the workforce here by exporting American jobs to China.

The crowd booed, on cue.

"Fact is, he may have changed his address but he hasn't changed his stripes. New Hampshire is not for sale and New Hampshire is not Scott Brown's consolation prize," she continued, alluding to his 2012 loss to Elizabeth Warren.

Brown spoke to an upbeat crowd of supporters in Concord late Tuesday evening in a speech that stretched for about 20 minutes, touching on a number of topics but focused squarely on his Democratic rival.

"Nobody in the Senate is more invested in the policies and failures of President Obama than Senator Shaheen," he said, standing in front of a large image of an American flag. "Listen, they campaigned together in our state six years ago. They were elected on the same day. And from that day to this day, she has voted for the failed Obama agenda more than 99 percent of the time," he said, emphasizing the salient number. The crowd booed, on cue.

New Hampshire Republican strategist Jim Merrill said the incumbent was trying to run as locally focused an effort as possible, "like she's in a campaign for mayor of New Hampshire."


Shaheen aides and allies see that emphasis as an inherent advantage. "There's nothing [Brown] can point to and say: 'I've done that for New Hampshire,' " said campaign spokesman Harrell Kirstein . "We can."

Brown, for his part, has spoken about what he could do for the state and how it would be to New Hampshire's benefit to have "an independent voice" who doesn't vote with the president so frequently.

He has recently held six in-person town halls, a New Hampshire tradition that gives voters a chance to ask politicos anything, and has repeatedly criticized Shaheen for not hosting any similar events. At those forums, and others, he often speaks about federal issues — such as Obama's health care overhaul — while connecting them to their impact on the state.

While analysts said the specifics of the campaign will matter, the New Hampshire race is part of a furious nationwide battle for control of the US Senate, where the GOP must pick up a net of six seats in this year's midterm elections to win the chamber.

National factors, which currently favor Republicans as likely voters sour on Obama, could have a significant impact in the Granite State, which often swings with the broader political winds.

Stuart Rothenberg, a nonpartisan political analyst who closely follows US Senate races, said he was not convinced that the Republican wave would be enough to carry Brown. Still, he said, if the national environment is extremely good for the GOP, Brown "can win, but he's going need a strong wind at his back."


Polling has found the race to be competitive. One poll, conducted in August by the University of New Hampshire Survey Center, found the race to be a dead heat. Other recent surveys have found Shaheen with a single-digit lead.

Juliana Bergeron, the Republican national committeewoman for New Hampshire, said Brown was the underdog, as Shaheen is well known from her years in the public eye as a US senator, governor, and state senator. But Brown, she said, "is trending up."

Wherever the race stands, it is set to become substantially more heated.

"Let's go," Brown said as he finished his speech Tuesday night. "Let the games begin!"

Globe correspondent Carol Robidoux contributed to this report. Joshua Miller can be reached at joshua.miller@globe.com. Follow him on Twitter @jm_bos.