Democratic challenger Elizabeth Warren (48 percent) has overtaken incumbent Republican Scott Brown (44 percent), in a Senate squeaker that still falls within the margin of error, according to a Suffolk University/7NEWS (WHDH-Boston) poll of likely general election voters in Massachusetts. Eight percent of those polled were undecided or chose someone else.

These results contrast with a Suffolk University/7NEWS poll conducted in May, when Brown led Warren 48 percent to 47 percent, with 5 percent either undecided or choosing someone else.

“Fresh off a new TV ad buy and a prime time convention speech, Elizabeth Warren has improved her popularity and overtaken Scott Brown head-to-head,” said David Paleologos, director of the Suffolk University Political Research Center in Boston. “She enters the debate phase of the Senate campaign as the slight favorite, but the race is still fluid, and to win she must avoid peaking too soon.”

Presidential race

Meanwhile Mitt Romney, the former governor of Massachusetts, is lagging far behind Barack Obama in the presidential race here. Obama (64 percent) is leading Romney (31 percent) by 33 points among likely Massachusetts voters. Two other candidates will be listed on the Massachusetts ballot. Green Party nominee Jill Stein garnered 2 percent and Libertarian Gary Johnson 1 percent, with 4 percent undecided.

The survey also showed a likelihood that all three ballot questions will pass, but voters only became aware of their content in July, so opinions may change.

Favorability in U.S. Senate race

Brown’s net favorability was +31 compared to +30 in May, virtually unchanged. Warren’s jumped from +10 in May (43 percent favorable to 33 percent unfavorable) to +19 today (52 percent favorable to 33 percent unfavorable).

Brown’s cross-over support also is waning. In May, 24 percent of Obama voters said they would cross parties to vote for Brown, but today 19 percent said they would cross over.

“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, whose district includes Southeastern Mass. Warren benefited not only from her own speech, but from the oratory of others, both inside and outside of Massachusetts.”

One poll finding that could tip a close race back to Brown is the preference of general election voters of all parties for having one Democratic and one Republican Senator in Washington. Fifty percent said there is a benefit to having a member of each party representing Massachusetts in Washington DC, while 45 percent said it didn’t matter.

“Call it the party-parity-paradox,” said Paleologos. “Likely voters of all parties see a benefit to having Democrat John Kerry and Republican Scott Brown representing Massachusetts in the U.S. Senate.”

Ballot questions

Seventy-nine percent of likely voters supported the proposed Availability of Motor Vehicle Repair Information law, which would require auto manufacturers to allow auto owners and independent repair shops access to the same vehicle diagnostic and repair information made available to auto dealers and authorized repair facilities.

Nearly two-thirds (64 percent) supported the proposed Prescribing Medication to End Life law, which would allow Massachusetts licensed physicians to prescribe life-ending medication at the request of terminally ill patients meeting certain conditions.

And 59 percent supported the proposed Medical Use of Marijuana law, while 35 percent were opposed.

On Jan. 14, 2010, Suffolk University was the first poll using live interviews to show Republican Scott Brown leading Democrat Martha Coakley – by 4 points. Five days later, Brown won by 5 points on Election Day.

Methodology

The statewide survey of 600 likely Massachusetts general election voters was conducted September 13-16, 2012, using live telephone interviews of landline and cell phone users. The margin of error is +/-4 percent at a 95 percent level of confidence. Marginals and cross-tabulation data will be posted at 11 p.m. Monday, Sept. 17, 2012, on the Suffolk University Political Research Center Web site. For more information, contact David Paleologos at 781-290-9310, or follow on Twitter @davidpaleologos.