BOSTON (AP) — A new poll is showing the state’s closely-watched U.S. Senate race remains tight.
The Suffolk University and WHDH-TV poll released Monday shows Democrat Elizabeth Warren is the choice of 48 percent of likely general election voters in Massachusetts compared to 44 percent for incumbent Republican Sen. Scott Brown.
That’s within the poll’s margin of error.
Suffolk University Political Research Center Director David Paleologos said the poll reflects an uptick in Warren’s popularity after her speech at the Democratic National Convention and new television ads.
Paleologos cautioned that the race remains unpredictable.
‘‘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,’’ Paleologos said.
The two face off for their first debate on Thursday.
The poll also shows voters favoring three ballot questions.
According to the survey, 59 percent of likely voters backed a question that would legalize the medical use of marijuana. The measure calls for the state to register up to 35 nonprofit medical treatment centers to distribute the marijuana.
Nearly two-thirds of voters, 64 percent, supported another question that would allow terminally ill adults to self-administer a life-ending drug.
The widest margin, 79 percent, backed a question what would require car makers to provide independent repair shops with access to their diagnostic systems. State lawmakers have approved a compromise on the question and both sides are now urging voters to reject the so-called ‘‘Right to Repair’’ question.
The poll also gave President Barack Obama a 33-point margin over former Gov. Mitt Romney in his home state, with 64 percent of likely voters backing Obama and 31 backing Romney.
The statewide survey of 600 likely general election voters was conducted Sept. 13-16 and had a margin of error of plus or minus four percentage points.
The poll was released as both candidates took to the campaign trail Monday to cast themselves as friendly to small businesses.
In a stop in Boston’s Dorchester neighborhood, Warren launched what she called the ‘‘Small Businesses for Elizabeth’’ group. Warren, echoing a familiar campaign theme, said Washington is ‘‘rigged to work for the big guys.’’
‘‘I want to be here to fight for small businesses,’’ she told supporters.
Brown also made a pitch to small business owners at a morning event in the city’s Mattapan neighborhood, delivering doughnuts and coffee to employees at Auto Service and Tire.
During the stop Brown tried to portray Warren as anti-business.
‘‘She is the founder of that radical occupy protest movement,’’ Brown told reporters, adding that, ‘‘she’s pushing that mentality of you didn’t build it on your own.’’
Also Monday, Brown released a new 30-second television ad geared at appealing to women voters. The ad features a series of women offering testimonials for Brown, saying he supports abortion rights and will work to make life better for families.
Warren’s campaign has tried to portray Brown as unreliable on women’s issues, pointing to his vote earlier this year to block a Democratic bill calling for equal pay in the workplace. Massachusetts Citizens for Life, the state’s largest anti-abortion group, is also supporting Brown.
The Senate race is already the most expensive political contest in Massachusetts history.