State Sen. Scott Brown (R) garnered more than 50 percent of the vote for Tuesday’s Massachusetts Senate special election in a new survey of likely voters conducted over the weekend by Public Policy Polling.Brown, who just weeks ago was considered a long-shot for the seat, leads Massachusetts Attorney General Martha Coakley (D) 51 to 46 percent in the new poll, with 4 percent undecided. The margin of error is 2.8 points.And though Brown’s unfavorable rating has risen, he is still viewed favorably by far more likely voters — 56 percent have a favorable view of him compared to 37 percent with an unfavorable view.Coakley, in contrast, now has a net negative favorability rating. Forty-four percent view her favorably and 51 percent unfavorably, according to the poll, a significant swing from the fall when she was widely popular among the electorate. Even a week ago, Coakley’s favorability ratio was a positive 50 to 42 percent.The likely electorate for Tuesday’s election is skeptical of the Democratic agenda in Washington. Forty-eight percent oppose the Democrats’ health care proposal while 40 percent say they support it. And likely voters are split on President Barack Obama — 44 percent approve and 43 percent disapprove of his job performance.Among those who voted for Obama in the 2008 presidential race, 76 percent support Coakley, but 20 percent are backing Brown.The task of the Coakley campaign, then, is to rally more solid Democrats, who appear less inclined to vote. But she has her work cut out for her: 89 percent of Republicans say they are “very excited— to go vote compared to 63 percent of Democrats responding to the poll.And while 63 percent of likely voters said they approve of the work the late Sen. Edward Kennedy (D-Mass.) did during his four-plus decades in the Senate, just 47 percent said they would like to see Massachusetts’ next Senator carry on his legacy. Forty-one percent do not.