Sen. Roy Blunt (R-MO) introduced the legislation so that companies could opt out on moral or religious grounds. Romney said "I'm not for the bill," during an interview on Wednesday.
Later that same day he reversed himself in a second interview, saying he misunderstood the question.
"Of course I support the Blunt amendment. I thought he was talking about some state law that prevented people from getting contraception so I was simply — misunderstood the question and of course I support the Blunt amendment."
This misstep drew criticism from L. Brent Bozell, chairman of the conservative leaning ForAmerica, which promotes small government.
“Mitt Romney's inability to answer a reporter's question about Sen. Blunt's Respect for Rights of Conscience Act is a major blunder and will not go unnoticed by conservatives,” he said.
The Obama deputy campaign manager Stephanie Cutter jumped in, too. She said Romney's remarks "showed why women don't trust him for one minute."
"It took little more than an hour for him to commit his latest flip-flop. Even worse, he ended up on the wrong side of an issue of critical importance to women," she added.
The misstep follows on the heels of Romney's success in Tuesday's primaries in Arizona and Michigan.
It is unclear what Romney's changing stance will mean for his campaign, but the bill itself doesn't appear to have a future. The Senate voted today to kill the proposal by a 51-48 vote.