"Are those the values we want in an American president?" the narrator asks.
The Priorities USA spot will air in Detroit and Flint through the Michigan primary next Tuesday.
Romney was initially expected to walk away with the state's primary considering his ties to the area — his father served as governor and Romney grew up in the state. But wins by Rick Santorum in other Midwestern states like Iowa, Missouri and Minnesota threw Romney's inevitability argument into question, while his continued insistence that he would not support the popular auto bailout has tarnished his image.
A loss would be potentially devastating to Romney's campaign, which could easily explain why the Obama-friendly group is on the attack.
Recent polling in the state show the candidates are neck-and-neck; Santorum had begun to pull away in the polls before Romney began spending a sizable amount of time and money in the state.