The Massachusetts Republican, who has been hinting for months he would challenge Sen. Jeanne Shaheen, D-N.H., is expected to announce the formation of an exploratory committee in a speech to a New Hampshire GOP conference Friday.
An exploratory committee allows him to hire staff and raise money for a run in this fall's election, an advisor said. The advisor confirmed that Brown had cancelled a planned trip to Iowa next month, where he was scheduled to headline a GOP fundraiser.
In addition to Brown, plenty of potential 2016 candidates will make appearances at the Northeast Republican Leadership Conference in Nashua, N.H., this weekend, including Louisiana Gov. Bobby Jindal and former Pennsylvania Sen. Rick Santorum.
Brown has long owned a vacation him in the Granite State, but sold his Massachusetts home and moved there full-time in December. He has continued to work out of the Boston-based law office of Nixon Peabody LLP, as he is not licensed to practice in New Hampshire.
Republicans are hopeful Brown may lead a charge to flip the Senate this year. Democrats hold a 55-45 majority in the Senate, including two independents who caucus with the Democrats, but are defending 21 of the 36 seats up for reelection this year.
The GOP has strong chances to pick up seats in South Dakota and West Virginia, with opportunities in Alaska, Arkansas, Louisiana, Montana, and North Carolina, while Democrats are eyeing openings just in Georgia and Kentucky.
Brown, who was elected to fill the late Sen. Ted Kennedy's seat in the Bay State in 2010, has proved his ability to win over Independents and independent-leaning Democrats, even in a state as blue as Massachusetts.
Still, Brown's opponent in 2010, Attorney General Martha Coakley (who is running for governor this year), was considered a weak opponent who ran a lackluster campaign. And while Shaheen is seen as a target because of her support of the Affordable Care Act, she served as New Hampshire's governor for three terms and defeated incumbent Sen. John Sununu, 52 percent to 45 percent in 2008.
Early polling shows Brown easily defeating his primary opponents, but has Shaheen leading Brown by margins ranging from 5 points to as much as 13 points.