President Barack Obama is pushing an economic fairness argument to voters in Colorado while Republican Mitt Romney's campaign protests a tough attack ad aired by a super PAC supporting the president.
Romney campaign spokeswoman Andrea Saul is labeling as "despicable" the ad linking Romney to a woman's death from cancer.
The Obama campaign is refusing to call on Priorities USA Action to pull the TV spot. A former White House aide and co-founder of the group, Bill Burton, is defending the ad.
Obama is rallying supporters in Pueblo and Colorado Springs on Thursday. Romney is raising money in New York as his campaign prepares for a bus trip through battleground states and a decision on a running mate.