Updated: 11:24 a.m. ET
(CBS News) Elizabeth Warren is directly combating allegations that she improperly identified as Native American to further her career, releasing a new 30-second-spot in which she addresses the issue head on.
"Let me be clear. I never asked for, never got any benefit because of my heritage. The people who hired me have all said they didn't even know about it," the Massachusetts Senate candidate says in the spot. "Scott Brown can continue attacking my family, but I'm going to keep fighting for yours."
The ad is a direct response to an ad released Monday by her rival, incumbent Republican Sen. Scott Brown, which. Warren has said she is Native American, and listed herself as such in some professional forms in the past, but has not offered up documentation proving that she is an official member of the Native American community. Brown has hammered Warren over the allegations for months, and during a debate last week called on her to produce evidence that she did not benefit professionally from her claims to Native American lineage.
In the spot, Warren says she doesn't have proof of her Native American roots because, "as a kid, I never asked my mom for documentation when she talked about our Native American heritage. What kid would?"
"But I knew my father's family didn't like that she was part Cherokee and part Delaware. So my parents had to elope," she continued.
In what has become one of the most closely-watched races in the country, Warren and Brown have been deadlocked in the polls for months. But as Warren made apparent gains following the Democratic National Convention, the campaign took a particularly nasty turn. Brown's new ad was the first character assault of the race, and both have released negative ads.
Warren on Monday sent a fundraising email to supporters yesterday defending her record and lambasting the Brown campaign for the advertisement - which she cast as "an ugly, nasty attack on my family and our heritage."
Boston's WCVB.com, meanwhile, has unearthed video of Brown staffers doing American Indian "war whoops" and making "tomahawk chops" at a rally for the senator this week.
And a new report in the Boston Globe notes that Warren in the 1990s helped draft a petition to the Supreme Court on behalf of LTV Steel in its effort to avoid paying into a health care fund for retired coal miners.
The Warren campaign said the coal miners would still receive their full benefits and that the case was about bankruptcy principles, but according to the Globe, Warren's opponents in the case argued that the corporation was attempting to use bankruptcy laws to avoid paying their share of the health care.