BOSTON (AP) -- Former Sen. Scott Brown has confirmed he won't run in a Senate special election, dealing a blow to Republicans who hoped to steal the seat formerly held by Democrat John Kerry.
Brown released a statement Friday afternoon making his decision official.
"I was not at all certain that a third Senate campaign in less than four years, and the prospect of returning to a Congress even more partisan than the one I left, was really the best way for me to continue in public service at this time," he said. "And I know it's not the only way for me to advance the ideals and causes that matter most to me."
The decision likely means the Senate seat will stay in Democratic hands. GOP officials in Washington and Massachusetts widely considered Brown the strongest possible Republican candidate in a state that traditionally favors Democrats.
Brown won the 2010 special election for longtime Sen. Ted Kennedy's seat following his death, but lost a bruising re-election battle last year to Democratic Sen. Elizabeth Warren. The Republican remained popular among Massachusetts voters, still had a statewide political organization and demonstrated an ability to raise tens of millions in campaign donations.
Democrats already have two congressmen in the race to replace Kerry, who has resigned his seat to become secretary of state: U.S. Reps. Edward Markey and Stephen Lynch will face off in an April 30 primary.
Brown said his instinct was to run: "Over these past few weeks I have given serious thought about the possibility of running again, as events have created another vacancy requiring another special election," he said. "I have received a lot of encouragement from friends and supporters to become a candidate, and my competitive instincts were leading in the same direction."
Lynch, who formally entered the race on Thursday, issued a brief statement saying he understood Brown's reasons.
"He has basically been campaigning nonstop for three years. It's perfectly understandable that he wouldn't want to undertake another campaign," said Lynch.
The winner of the special election would have to face voters again in November 2014, when Kerry's current term expires.
With Brown out of the running, potential Republican candidates include former Gov. William Weld and former Lt. Gov. Kerry Healey.
Weld, who recently returned to Massachusetts to join the Boston law firm Mintz Levin, has said he would consider a run for the Senate if Brown did not seek the seat. He did not immediately return a call seeking comment.
A message was also left with Healey, who served as lieutenant governor from 2003-2007 under then-Gov. Mitt Romney and lost the governor's race to Democratic Gov. Deval Patrick in 2006.
Patrick this week named William "Mo" Cowan, a former top aide, to fill Kerry's seat on an interim basis until the election.
The general election is June 25.