By Josh Lederman - 05/09/12 09:06 PM EDT
The ad also uses footage of CBS News correspondent Leslie Stahl saying that Brown has "turned out to be unpredictably independent, and beholden to no one."
Absent from the ad is any mention of Brown's affiliation as a Republican, as is any reference to Warren.
Democrats and Republicans both attempted to keep negative stories about their opponent in the Senate race alive on Wednesday.
The Massachusetts Democratic Party lodged a complaint against Brown with a Senate ethics panel, claiming Brown violated a rule against using official resources for campaign purposes. The complaint argued that a member of Brown's congressional staff, while on official duty, filmed video of the senator that his campaign later used to promote him.
Meanwhile, Republicans attempted to escalate the controversy over Warren's claim to Native American heritage and whether she used that claim to further her career. Republicans circulated a Boston Herald story that quoted a genealogist alleging that Warren's great-great-great-grandfather served in a Tennessee militia unit that "rounded up Cherokees" during the Trail of Tears.
The Hill rates this race a toss-up.