The American Medical Association, the nations largest doctors group, opposes the Senate health care bill, the organization announced in a letter to Senate leaders Monday.

Medicine has long operated under the precept of Primum non nocere, or first, do no harm. The draft legislation violates that standard on many levels, American Medical Association CEO James Madara wrote to Senate Majority Leader Mitch McConnell (R-Ky.) and Senate Minority Leader Chuck Schumer (D-N.Y.).

The American Medical Association is the latest health care sector group to express opposition to, or at least serious concerns with, the Senate bill, known as the Better Care Reconciliation Act . McConnell unveiled the bill Thursday and aims to bring it to the Senate floor for a final vote as soon as this week. With 52 Republicans in the Senate, McConnell can only lose two GOP votes if he wants to get the 50 needed to advance the bill. Five Republican senators , however, are already on record against it.

The physicians lobbying organization cites numerous problems with the Senate GOP bill, starting with its likely effect of causing many millions of currently insured Americans to lose their health coverage and be unable to afford medical treatments.

It seems highly likely that a combination of smaller subsidies resulting from lower benchmarks and the increased likelihood of waivers of important protections such as required benefits, actuarial value standards, and out of pocket spending limits will expose low and middle income patients to higher costs and greater difficulty in affording care, the AMAs letter says.

The group also takes issue with the legislations deep cuts to federal Medicaid spending.

The Senate proposal to artificially limit the growth of Medicaid expenditures below even the rate of medical inflation threatens to limit states ability to address the health care needs of their most vulnerable citizens, the letter says.

The legislation would make tax credits for private health insurance created by the Affordable Care Act available to fewer people, reduce their value and tie them to plans that have larger deductibles and higher out-of-pocket costs than the policies sold under Affordable Care Act rules.

The bill also would permit states to make sweeping changes to insurance market rules, which would allow insurers to offer very skimpy plans that dont come with a basic set of guaranteed benefits and that could exclude treatments and medicines for people with high-cost ailments.

Although insurers would still be forbidden to reject customers with pre-existing conditions or charge them higher rates as is the case under the Affordable Care Act relaxing the benefit rules and introducing plans that require patients to pay more out-of-pocket would make the coverage less valuable, especially to people with pre-existing conditions.

The Senate bill would undo the Affordable Care Acts expansion of Medicaid and end the current open-ended federal commitment to pay more than half the expense of covering any eligible Medicaid enrollee. Instead, federal Medicaid funding would be capped at a flat amount per person or a flat amount per state, based on a states preference, that would grow more slowly than current Medicaid spending and more slowly than rising health care costs overall.

The Congressional Budget Office analysis of the Senate bill is scheduled to be released Monday. The CBO earlier concluded that the House-passed American Health Care Act , which is similar to the Senate measure, would lead to 23 million fewer people having health coverage over the next 10 years.

We sincerely hope that the Senate will take this opportunity to change the course of the current debate and work to fix problems with the current system. We believe that Congress should be working to increase the number of Americans with access to quality, affordable health insurance instead of pursuing policies that have the opposite effect, and we renew our commitment to work with you in that endeavor, the AMAs letter concludes.

Also on Monday, the National Association of Medicaid Directors, which represents the state officials who oversee the program, rejected the Medicaid components of the Senate bill .

The legislation would give states greater leeway to decide who is eligible for Medicaid and what benefits the program must cover, but these regulators argue that flexibility doesnt make up for the much lower funding amounts. Several governors have expressed similar concerns.

No amount of administrative or regulatory flexibility can compensate for the federal spending reductions that would occur as a result of this bill, the Medicaid officials said in a statement.

Changes in the federal responsibility for financing the program must be accompanied by clearly articulated statutory changes to Medicaid to enable states to operate effectively under a cap, they went on. The Senate bill does not accomplish that. It would be a transfer of risk, responsibility, and cost to the states of historic proportions.

The National Governors Association, which represents state chief executives from both parties, also weighed in on the Senate bill Monday, urging McConnell to slow down.

Governors must be given adequate time to determine the impact any health care bill will have on their states and residents, and ensure that the bill does not adversely harm the people we were elected to serve, Virginia Gov. Terry McAuliffe (D) and Massachusetts Gov. Charlie Baker (R) wrote to McConnell on behalf of all 50 governors. We urge you to give states sufficient time to review the legislation before proceeding, so that the full impact of the legislation may be understood and explained to the American people.

Numerous other health care groups also have misgivings or are outright opposed to passage of the Senate health care bill. They include:

The American Academy of Family Physicians

The American Academy of Pediatrics

The American Hospital Association

The Federation of American Hospitals

The Childrens Hospital Association

Americas Essential Hospitals

The Catholic Health Association of the United States

The American Cancer Society Action Network

The American Lung Association

AARP

This story has been updated to include information from the National Governors Association.

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