Updated

Sen. John McCain is urging senior citizens to cut up their AARP membership cards and mail the pieces back to the organization, claiming AARP has betrayed them.

Citing AARP's past opposition to proposed cuts in Medicare, McCain expressed dismay Thursday that the senior group has suddenly changed its position to support $460 billion in cuts to the program proposed by Democrats to help pay for health care legislation.

"Shame on AARP," McCain, R-Ariz., said Thursday on the Senate floor. "Take your AARP card, cut it in half and send it back. They've betrayed you."

"If we're talking about Medicare cuts alone as a way of financing health reform, we would fight that with all of our strength," he added. "We've gone as far as we can down that road."

Democrats throughout Thursday's Senate debate used AARP's endorsement of their bill to blunt Republican charges that they are gutting Medicare. AARP rode to the rescue of Democrats on Wednesday, announcing its support for billions in Medicare cuts to help fund the legislation.

As Republicans pressed to restore the cuts, AARP said Democrats merely were recommending elimination of waste and inefficiency within the giant health care program for seniors.

"Most importantly, the legislation does not reduce any guaranteed Medicare benefits," A. Barry Rand, AARP's CEO, said in a letter to senators.

Republicans, led by McCain, 73, but not a member of the group, said seniors would lose some of their add-on benefits that are part of coverage under private insurance Medicare. "Above all, we must not use Medicare as a piggy bank" to pay for other programs, he said.

Democrats, sensitive to the charges, rallied behind an alternative proposal by Sen. Michael Bennet, D-Colo., saying the bill would cause no reduction in guaranteed Medicare benefits.

Fox News' Mike Majchrowitz and the Associated Press contributed to this report.