A coalition of groups representing insurance companies, doctors and hospitals are calling on Congressional leaders to abandon their latest efforts to repeal the Affordable Care Act requirement that all individuals carry health insurance, saying it will destabilize the market and raise premiums.

The groups on Tuesday sent the letter to House and Senate leaders after Senate leader Mitch McConnell announced plans to include the repeal in the upper chamber’s tax reform bill.

House leaders said they were meeting to decide whether to also add the individual mandate repeal to their bill, which could be up for a vote as soon as Thursday.

The letter, whose signatories include America’s Health Insurance Plans and the BlueCross BlueShield Association, echoes the concerns of many benefit provider and employer groups that repealing the individual mandate without other comprehensive reform will cause instability in the health insurance marketplace and shift costs to employers and other stable health insurance customers.

The American Benefits Council has also said that erosion of the ACA exchanges would make individual market coverage a less viable option for part time workers, early retirees and individuals looking for an option to COBRA coverage.

“We are urging you to maintain the individual mandate unless and until Congress can enact a package of reforms to adequately assure a balanced risk pool and prevent extraordinary premium increases,” said the letter, which was also signed by the American Medical Association, the American Academy of Family Physicians, the American Hospital Association and the Federation of American Hospitals.

“… Repealing the individual mandate without a workable alternative will reduce enrollment, further destabilizing an already fragile individual and small-group health insurance market on which more than 10 million Americans rely.”

Eliminating the requirement for individuals to purchase insurance would generate an estimated $338 billion in savings over 10 years by reducing government spending on health-coverage subsidies for an estimated 13 million Americans who would forgo coverage in 2027, according to an estimate from the Congressional Budget Office.

Bloomberg contributed to this report.