Seven Republican Senators have asked the Centers for Medicare & Medicaid Services to withdraw a proposed regulation creating accountable care organizations, according to a letter released Tuesday.

The letter cites “an increasingly diverse chorus of concerns many of our nation’s leading health care institutions have raised in recent days.” It is signed by Sens. Tom Coburn (R-OK), Jon Kyl (R-AZ), Mike Crapo (R-ID), Mike Enzi (R-WY), John Cornyn (R-TX), Pat Roberts (R-KS) and Richard Burr (R-NC). The correspondence was sent to HHS Secretary Kathleen Sebelius and CMS Director Donald Berwick, M.D.

While the Senators complimented the work put into the ACO draft, the letter states “based on the feedback we have received from providers around the country, we conclude that the proposed ACO regulation will fail to accomplish its purpose.”

Organizations, notably the American Hospital Association, have raised concerns about possibly high start up costs. CMS’ proposed program would allow healthcare providers to share in savings resulting from high-quality treatment, but the AHA has said the ACO start-up costs will be much higher than government estimates.