It is a rare unifying moment. Hospitals, doctors, health insurers and some consumer groups, with few exceptions, are speaking with one voice and urging significant changes to the Republican health care legislation that passed the House on Thursday.

The bill’s impact is wide-ranging, potentially affecting not only the millions who could lose coverage through deep cuts in Medicaid or no longer be able to afford to buy coverage in the state marketplaces. With states allowed to seek waivers from providing certain benefits, employers big and small could scale back what they pay for each year or reimpose lifetime limits on coverage. In particular, small businesses, some of which were strongly opposed to the Affordable Care Act, could be free to drop coverage with no penalty.

The prospect of millions of people unable to afford coverage led to an outcry from the health care industry as well as consumer groups. They found an uncommon ally in some insurers, who rely heavily on Medicaid and Medicare as mainstays of their business and hope the Senate will be more receptive to their concerns.

“The American Health Care Act needs important improvements to better protect low- and moderate-income families who rely on Medicaid or buy their own coverage,” Marilyn B. Tavenner, the chief executive of America’s Health Insurance Plans, the industry’s trade group, said in a strongly worded statement.