BOSTON — Former Massachusetts Sen. Scott Brown has begun seeking campaign staff while aggressively courting New Hampshire’s political elite, marking what local Republicans consider serious steps toward launching a Senate campaign against Democratic Sen. Jeanne Shaheen.

The stakes are high for the Republicans’ national push for the Senate majority this fall as well as for Brown’s own political ambitions.

The longtime Massachusetts resident, having recently relocated to his seacoast New Hampshire vacation home, is expected to launch an exploratory committee to enter the race as soon as Friday, according to several New Hampshire Republican officials who spoke directly to Brown about his plans. The move officially allows him to begin raising money and hiring staff.

Brown spent much of the past two weeks calling key New Hampshire Republican officials and influential Republican activists, saying he was going to run and seeking their support. At the same time, Brown’s camp has quietly begun offering paid positions to Republican operatives for a prospective New Hampshire campaign.

Several people involved in the discussions said some in the Republican establishment remain skeptical, given the former senator’s recent track record. The 54-year-old Brown angered Massachusetts Republicans last year after indicating he would run in the state’s special U.S. Senate election, only to change his mind late in the process.

“He’s been reaching out to opinion leaders, to grassroots activists, getting a sense of, ‘Would you be supporting a Scott Brown campaign,’” said former New Hampshire Rep. Frank Guinta, who is running again for Congress and was included in Brown’s outreach efforts. “That, to me, says he’s serious. But I think only Scott Brown knows if Scott Brown is going to run.”

Democrats hope he does not.

While recent polls give Shaheen a solid lead in a prospective matchup, Brown’s near-universal name recognition in a state that shares a media market with Massachusetts and his national fundraising network would make him a serious contender on Day One should he enter the race.

Shaheen, a former governor, was widely expected to win her first re-election test in November before Brown began hinting late last year that he might cross state lines to challenge her. National Democrats already have their hands full defending more vulnerable Democratic incumbents across the country as they fight to retain their six-seat Senate majority.

But Democrats and their allies are already preparing for a worst-case scenario, having spent roughly $360,000 combined on television advertising against Brown in recent weeks. Conservative critics spent heavily to weaken Shaheen earlier in the year, led by the tea party ally Americans For Prosperity, which spent roughly $700,000 on television ads knocking Shaheen’s support for President Obama’s health care overhaul.

Initial polls suggested a Brown-Shaheen matchup was essentially a tossup, but surveys conducted more recently after the anti-Brown ads give Shaheen a significant lead.

Whether he runs or not, there are risks for Brown, who is also hinting at a 2016 presidential run. He is due to visit Iowa later in the month.

Some believe Brown’s political future could suffer permanent damage should he ultimately disappoint New Hampshire Republicans by backing out of the Senate race after so much hoopla.

But should he run and lose, Brown’s resume would be tainted with two high-profile losses in two years.