(Corrects headline to say Brown will not seek seat)
BOSTON, Feb 1 (Reuters) - Former Republican Senator Scott Brown has decided not to run in the June special election to fill the Massachusetts U.S. Senate seat being vacated by John Kerry, local media reported on Friday, a move likely to dim Republican chances of picking up the traditionally Democratic-held seat.
The Boston Herald reported it had received a text message from Brown reporting that the paper was "the first to know" of his plans not to seek the seat.
Democrat Kerry is leaving the Senate to become U.S. secretary of state.
Brown stunned the state's liberal establishment in 2010 when he won a special election to fill the seat held by the late Edward Kennedy, becoming Massachusetts's first Republican senator in three decades.
He left the Senate in January after he lost a re-election bid to Democrat Elizabeth Warren, a former Harvard professor.
Brown had been under pressure from local party officials to either launch a formal campaign or step aside to clear the way for an April 30 primary ahead of the June 25 special election.
So far two Democratic U.S. representatives, Edward Markey and Stephen Lynch, have declared their candidacies.
Recent polls of likely voters showed Brown with a modest lead over Markey and a stronger lead over Lynch in a theoretical general election matchup. (Reporting by Scott Malone; Editing by Vicki Allen)