It was, by all accounts, the most politically volatile amendment proposed to the health care legislation so far: a proposal by Senator Tom Coburn, Republican of Oklahoma, to bar federal health programs and the future federally regulated insurance exchanges from covering the cost of erectile dysfunction medication for convicted sex offenders.

Mr. Coburn, arguing for his amendment, said it was a step intended to save taxpayers’ money. The proposal, he said, “creates a prohibition so that erectile dysfunction drugs are not paid for by the American taxpayers” for “convicted rapists” and “pedophiles in this country.”

Senator Max Baucus, Democrat of Montana and chairman of the Finance Committee, said, “The amendment offered by the senator from Oklahoma makes a mockery of this Senate.” He added, “It’s a crass political stunt aimed at making 30-second commercials, not public policy.”

The Senate voted to kill the amendment, by 57 to 42. All 57 votes in favor of dismissing the amendment were by Democrats, while two Democrats joined 40 Republicans in supporting Mr. Coburn’s proposal. They were Senators Evan Bayh of Indiana and Ben Nelson of Nebraska.