The Senate just passed an amendment offered by Sen. Barbara Mikulski that would force insurers to cover women’s preventive care services such as mammograms without charging co-pays.

The amendment, which passed 61 to 39, came in repsponse to controversial recommendations by the U.S Preventive Services Task Force, which advised women to wait until 50 to start getting mammograms. A Republican alternative offered by Lisa Murkowski, that would have blocked recommendations of the task force from being used to ration care, was defeated 59 to 41.

While the Mikulski amendment promises free screenings to women, in reality, nothing is free — adding additional benefit mandates to insurance policies will just drive up premiums. And the provision leaves it up to the Department of Health and Human Services to determine which services must be covered, leading to concerns among abortion opponents that it could pave the way for federally funded abortion if HHS simply defines the procedure as preventive care for women.

UPDATE. In case you were wondering, Sen. Olympia Snowe broke with Republicans to vote for the Mikulski amendment, and Sen. Ben Nelson broke with Democrats to vote for the Murkowski amendment.