In an email to supporters in February, Sen. Scott Brown (R) wrote: “I know I am the underdog in this race.” For the first time in his fiercely fought contest with Democratic nominee Elizabeth Warren, the data supports his assertion.

Warren led Brown in a series of recent polls. A nonpartisan Western New England University poll of likely voters conducted Sept. 6-13 found Warren leading by 6 points, 50 percent to Brown’s 44 percent. A nonpartisan Suffolk University poll of likely voters conducted Sept. 13-16 found Warren leading Brown by 4 points, 48 percent to 44 percent. And a poll from the Democratic-leaning Public Policy Polling conducted Sept. 13-16 found Warren leading by 2 points, 48 percent to 46 percent.

Warren, who appeared in prime time during the Democratic National Convention early this month, has recently tweaked her campaign messaging. She was the first candidate in the race to go up on TV with a negative spot. And she has taken a new tack in her direct-to-camera appeals.

“Scott Brown’s not a bad guy — he doesn’t always vote the wrong way. But too often, on things that really matter, he’s not with you,” she says in a 60-second spot that began airing statewide Tuesday.

That first clause appears to be an acknowledgment that a majority of likely voters in the Bay State continue to have a positive view of Brown. Indeed, polls show voters continue to view Brown quite favorably. Warren is also seen positively, but more respondents had not yet formed an opinion of her.

The Suffolk University poll surveyed 600 likely voters by land line and cellphone using professional interviewers and had a margin of error of 4 points. The Western New England University poll surveyed 444 likely voters by land line and cellphone using trained student interviewers and had a margin of error of 4.6 points. The PPP poll surveyed 876 likely voters using robocalls to land lines only — a polling strategy that is not considered as accurate as using live interviewers — and had a margin of error of 3.3 points.

Roll Call rates the Massachusetts Senate race as a Tossup.