A new poll released tonight showed presumptive Democratic nominee Elizabeth Warren leading Sen. Scott Brown (R-Mass.) in a horse race matchup.

Among registered voters, 49 percent said they would vote for the Harvard professor and 42 percent said they would vote for Brown “if the election … were being held today.” Those numbers included those who leaned more toward one candidate or the other. Six percent were undecided.

Eleven months before polls open, Warren and Brown had similar bases of strong support. Twenty-four percent of registered voters said they would definitely vote for Warren, while 21 percent said they would definitely vote for Brown.

The University of Massachusetts Lowell-Boston Herald poll also found Warren still had room to build name identification across the state. While 23 percent had never heard of Warren, only 4 percent had never heard of Brown.

Brown, who rocketed to stardom during his upset 2010 special election victory over Democrat Martha Coakley, received intense media coverage in the days after he was elected to fill the open seat of the late Sen. Ted Kennedy (D).

In the poll, 48 percent of registered voters had a favorable opinion of Brown while 35 had an unfavorable opinion. The split for Warren was 34 percent favorable, 27 percent unfavorable. In Democratic Massachusetts, President Barack Obama earned a favorability rating of 61 percent. Former Massachusetts Gov. Mitt Romney (R), who hopes to replace Obama in 2013, was viewed favorably by only 40 percent of those polled.

Separate from favorability, Brown’s job approval has sunk 8 points since a September UMass-Herald poll. Forty-five percent now approve of “the way Scott Brown is handling his job as U.S. Senator.”

The poll of 505 registered Bay State voters was conducted Dec. 1 to Tuesday by telephone interview and had a margin of error of 5.3 points.

Roll Call rates the Massachusetts Senate race a tossup.