Washington, DC (LifeNews.com) -- It appears the Barack Obama campaign has released a new radio ad bashing presidential candidate John McCain on stem cell research. The ad claims McCain has held up stem cell research even though the Arizona senator has repeatedly voted for it.

The ad is airing in Colorado and could be airing in other battleground states, but the Obama campaign has apparently not sent out an official press release with details of the spot.

According to the web site Politico, the ad apparently says McCain has "stood in the way of progress" on stem cell science, despite McCain's repeated votes to authorize millions for it.

The McCain campaign ran its own ad touting McCain's support for stem cell research earlier this month.

"John McCain will lead his Congressional allies to improve America's health," the ad says.

"Stem cell research to unlock the mystery of cancer, diabetes, heart disease; stem cell research to help free families from the fear and devastation of illness; stem cell research to help doctors repair spinal cord damage, knee injuries, serious burns; stem cell research to help stroke victims," it explains.

"And, John McCain and his Congressional allies will invest millions more in new NIH medical research to prevent disease," the ad continues. "Medical breakthroughs to help you get better, faster. Change is coming."

McCain and Obama have some strong disagreements when it comes to bioethics issues, with McCain supporting a ban on all forms of human cloning and opposing the purposeful creation of human embryos for their destruction. Obama is on the opposite side.

The Obama campaign has a history of using radio ads to hit on touchy subjects without drawing much attention from the mainstream media.

Earlier this month, he went after McCain on abortion with claims that women’s lives and health will be at risk should Roe be overturned.

Sign Up for Free Pro-Life News From LifeNews.com