Warren released her first negative TV ad targeting Brown on Sept. 13, the first day of interviews for the poll. The previous week, she spoke in prime-time at the Democratic National Convention. In the wake of the convention, President Obama has seen a bounce in his poll numbers, and other Democratic Senate candidates have seen good post-convention numbers in states like Ohio and Florida. A big problem for Brown: Mitt Romney, the former governor of Massachusetts, lags badly behind Obama in the presidential race. Obama leads Romney by 33 points in Massachusetts -- 64 percent to 31 percent. And Brown's cross-over support has decreased since the May poll. In that earlier survey, 24 percent of Obama voters said they would vote for Brown, while in the latest survey 19 percent said they would do so. Brown faces a tall order in winning the race if Romney fails to make up any ground against Obama in the state -- and in fact the GOP presidential nominee has lost a little ground since the May poll, where Obama led 59 percent to 34 percent. "The Democratic National Convention appears to have connected the dots for some voters in Massachusetts," said Paleologos. "They've linked Barack Obama, Bill Clinton, Elizabeth Warren and Congressional candidate Joseph Kennedy. ... Warren benefited not only from her own speech, but from the oratory of others, both inside and outside of Massachusetts." Brown still has high favorability numbers, showing the importance for Warren of running negative ads focused on her opponent. A whopping 60 percent of voters hold a favorable view of the incumbent, while 29 percent hold an unfavorable view. Meanwhile, Warren is viewed favorably by 52 percent of respondents, while 33 percent viewed her unfavorably. One question in the poll indicates that the national controversy stemming from Missouri GOP Senate nominee Todd Akin's comments on "legitimate" rape rarely leading to pregnancy may have hurt Brown. Although the Massachusetts senator tried to get out in front of the issue -- he was the first Republican to call for Akin to resign from the race -- 36 percent of respondents answered that the "recent national controversy over abortion" made them less likely to vote for Brown. Eleven percent said it made them more likely to, while 42 percent said it made no difference. The Suffolk University/WHDH-TV poll was conducted Sept. 13-16, surveying 600 likely voters, for a margin of error of plus-or-minus 4 percentage points.