The majority of likely Massachusetts voters have a favorable opinion of Sen. Scott Brown (R), according to a new poll released today.

Fifty-four percent of those polled said they had a favorable view of Brown, while 25 percent had an unfavorable view of the state’s junior Senator. Brown, who won an unexpected victory in a January 2010 special election, is extremely well-known in the state. Only 5 percent of those surveyed said they hadn’t heard of him   

The WBUR poll, conducted by MassINC polling group, showed Brown ahead of Harvard professor Elizabeth Warren in a theoretical matchup.

If the election were held today, 44 percent said they would vote for Brown, 35 percent said they would cast their ballot for Warren and 18 percent said they did not know.

Warren, who until August was charged with ramping up the Consumer Financial Protection Bureau, appears set to join the crowded Democratic field to take on Brown. She received a warm reception at a speech she gave to union members and activists Monday, getting a standing ovation when she alluded to a possible Senate bid.

Brown was well ahead in other horse-race matchups with declared Democratic candidates, none of whom are known statewide, in the poll. Brown polled at 46 percent against Newton Mayor Setti Warren, who got 28 percent; Brown pulled 45 percent against City Year co-founder Alan Khazei, who got 30 percent; and the Senator received 45 percent versus activist Bob Massie, who got 29 percent.

The live telephone poll of 500 likely voters was conducted Aug. 30 to Sept. 1 and had a margin of error of 4.4 points. Roll Call Politics currently rates the race as a Tossup.