After months of shadow boxing, the Massachusetts Senate campaign entered a more aggressive phase this week, as Republican Scott Brown and Democratic rival Elizabeth Warren went toe-to-toe with negative ads for the first time.
Both released new commercials and battled over a slew of issues — including abortion rights, equal pay for women, and taxes — which they believe will swing the few undecided voters in what is considered one of the more important and competitive Senate races in the country.
Warren is planning a major rally Saturday with Governor Deval Patrick and Representative Michael Capuano, a Somerville Democrat, at Boston University’s Morse Auditorium, in an attempt to demonstrate the enthusiasm of grass-roots supporters.
Brown was in Washington for much of the week and has no announced events for Saturday. But on Friday, he continued traveling the state trying to demonstrate bipartisan support, getting an endorsement by Rita Mercier, a Democratic city councilor and former mayor of Lowell.
The intensity of the race will pick up even more over the next week. On Thursday, the two will meet face-to-face for the first time when they debate on WBZ-TV. Their series of four televised debates could have a strong impact on the race’s outcome.
Warren, who has been reshaping her ad campaign, was the first to air a negative ad on Thursday. Her 30-second spot, through the voice and image of a plain-spoken Lowell boxing trainer, accuses Brown of ‘‘siding with the big-money guys’’ and advocating tax cuts for the wealthy.
Brown immediately responded with an ad released Friday that shows the senator dressed casually in a sweater, looking directly at the camera.
“Instead of talking about things that matter, like jobs, she’s being dishonest about who I am and what I stand for,” Brown says in the new spot. “Don’t be fooled by Elizabeth Warren’s negative attacks. Like a lot of you, I came from nothing. I’m on your side, fighting for the middle class.”
In between shots of Brown, the ad shows fuzzy images of Warren and warmer shots of Brown greeting voters.
Brown has been attacking Warren on a campaign website but had not previously mentioned her in an advertisement.
Brown’s spokesman, Colin Reed, said Warren’s charges about Brown’s support of tax cuts for the wealthy are distorted.
“Scott Brown wants to keep taxes low on everyone,’’ Reed said in an e-mail. “He wants to keep existing tax rates (that have been in effect for more than a decade) in place.’’
Warren’s campaign responded that Brown voted against President Obama’s plan to extend the Bush era tax cuts for most taxpayers because it excluded those earning $250,000 or more a year.
Brown repeated Friday in an interview with WTKK that he would not support an extension of the Bush tax cuts, even if there was no other option on the table, unless it included all taxpayers, because he said many in the top bracket create jobs.
Brown created an additional flare-up Friday when he released a second advertisement that promotes his stance on abortion and other women’s issues. Brown has long said he supports abortion rights, although he has received the endorsement of Massachusetts Citizens for Life, the state’s leading antiabortion group.
The second ad comes as the Massachusetts Republican State Committee decided Thursday night to put off a decision on whether to adopt the national party’s platform until after the November election. Massachusetts Republicans have traditionally been more socially liberal than the national party. The state GOP’s current platform does not make a reference to abortion.
Brown’s ad features a variety of women praising him.
“Scott Brown is prochoice, and he supports a woman’s right to choose,” one woman says.
“I like that Scott Brown is independent; he really thinks for himself,” says another.
As the women speak, Brown is shown wearing his famous barn jacket, standing in front of his home with his two daughters, his wife, and their dog.
“When my daughters grow up, I want to make sure that they have good jobs with equal pay, and I know Scott Brown will fight for that,” one woman says.
Brown voted with other Republicans in June to block the Paycheck Fairness Act, saying it would spark lawsuits and unreasonably hamper employers. The bill would have required employers to provide a reason for disparities in pay, among other new requirements.
Brown and Warren have competed fiercely over women’s issues because women are believed to be key swing voters in the closely fought election.
The ad provoked more rhetoric, most of it aimed at Brown from abortion rights groups weighing in from around the country. Warren has received the backing of several prominent groups that support abortion rights.
Warren supports legalized abortion in most cases, but her campaign spokeswoman, Alethea Harney said Warren would not try to overturn a federal ban on a late-term procedure that opponents call “partial birth abortion.” Harney did not say whether the candidate supported legalizing the procedure. Harney also said Warren supports the state’s parental notification requirement, which can be bypassed with the approval of a judge.
EMILY’S List, a national Democratic campaign group that supports candidates who favor abortion rights, including Warren, called the ad “shockingly dishonest.”
“Scott Brown is straight-up lying to Massachusetts voters with his latest ad,” the group said.
“Brown does not support a woman’s right to choose; his antichoice voting record has earned him the support of an antichoice organization in this very campaign,” said Stephanie Schriock, president of EMILY’s List. “And Brown does not support equal pay for women; he actually voted against the Paycheck Fairness Act.”
But the Brown campaign said the senator “has a strong record standing up for the issues important to women.”
“He is prochoice, supports good jobs with equal pay, and is an independent leader focused on turning this economy around for all of us,” said Alleigh Marre, a spokeswoman. “Attempts by professor Warren and her supporters to scare women voters won’t work. She should apologize for her negative campaign.”
Despite his endorsement by the state’s leading antiabortion group, Brown recently called on the Republican Party to remove strict antiabortion language from his platform. Brown was also the first Senate Republican to call on Missouri Senate candidate Todd Akin to abandon his campaign after Akin said that “legitimate rape” victims can physiologically prevent pregnancies.
Brown pledged during a press conference last month to “never vote in the Senate to curb women’s reproductive rights.”
But he has taken votes that have upset groups that favor abortion rights. Brown cosponsored the Blunt Amendment, which would allow health plans and employers to refuse to pay for contraception and other medical services if they have a religious or moral objection. He also opposed the Disclose Act, which would require independent political groups to disclose the names of donors who give more than $10,000. Antiabortion groups were strongly opposed to the act because they believed it curbed First Amendment rights.
Brown was on the defensive this week about a third ad, in which he says that President Obama signed into law a bill he filed to prevent members of Congress from using insider information to profit in the stock market. Though Brown filed a bill on the subject and worked on its passage, the version that reached Obama’s desk was introduced by Senator Joseph I. Lieberman, the Connecticut independent.Michael Levenson of the Globe
staff contributed to this report.
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