Several insurance groups sent a letter to Senate members late Thursday asking them to reject a proposal to repeal the antitrust protection afforded health insurers under the McCarran-Ferguson Act.

The letter was signed by the National Association of Insurance and Financial Advisors; the Council of Insurance Agents and Brokers; the Financial Services Roundtable; the Physician Insurers Association of America; and the Reinsurance Association of America.

The National Conference of Insurance Legislators also sent a letter to Senate members asking them to reject the amendment.

“NCOIL legislators again reaffirm our unwavering support for McCarran-Ferguson’s 1945 limited antitrust exemption, which in large part has contributed to the growth and health of our still-thriving insurance marketplace,” the letter said.

“We strongly caution against repeal,” the letter said. NCOIL also argued that “rolling back antitrust exemptions for health insurers would ignore already existing state antitrust protections and reduce competition while increasing costs.”

According to several insurance industry lobbyists, it is unlikely that a vote would occur on the proposal, an amendment to financial services reform legislation, because floor managers want to complete work on the legislation by Wednesday.

Sen. Dianne Feinstein, D-Calif., also has apparently dropped efforts to get a provision into the legislation that would give the U.S. Department of Health and Human Services the authority to allow state regulators to control health care insurance rates in states where regulators don’t now have such authority.

Currently, 26 states don’t give health insurance rate-regulation power to their insurance commissioners.

The bill Feinstein proposed would have extended authority to review rate increases to insurance regulators in those states and would have allowed them to deny increases they deemed unreasonable.

Similar legislation is being pushed in the House by Rep. Jan Schakowsky, D-Ill.

“The bill is not the right vehicle to accomplish my goal,” Feinstein said in a conference call convened by Health Care for America.

But Feinstein said she will continue to try to place her provision in other legislation–for example, tax legislation Congress hopes to complete work on before the Memorial Day recess.

“I’m concerned that until 2014, there’s nothing to stop these companies from raising premiums further, and this essentially would say that the HHS secretary could assure Americans that their rates are reasonable,” Feinstein said.

Health Care for America issued a report stating that health insurance industry profits rose 31% for the four largest health insurance companies over the last year.

But America’s Health Insurance Plans issued a statement denying that health insurance profits are unreasonable. AHIP compared the 3% overall profit margin for the industry with that of the pharmaceutical industry, which generated a 24% profit margin.

The McCarran-Ferguson amendment, No. 3823, had been slated for floor action Thursday but did not come up.

Debate continued Friday on another bill, S. 3217, the Restoring Financial Stability Act of 2010, but no votes on the measure were scheduled. The amendment is sponsored by Sen. Patrick Leahy, D-Vt.

For earlier coverage of the antitrust issue, please see Panel Rejects Antitrust Bill Amendment.