It would be a big mistake to call the legislation Senate Republicans released on Thursday a health care bill. It is, plain and simple, a plan to cut taxes for the wealthy by destroying critical federal programs that help provide health care to tens of millions of people.

The Senate majority leader, Mitch McConnell, and other Republicans have pitched the bill as a fix for the Affordable Care Act, or Obamacare. But their true ambition is not to reform Obamacare, which, whatever its shortcomings, has given 20 million Americans access to health insurance. If passed in its current form, the Senate bill would greatly weaken Medicaid, the federal-state program that provides insurance to nearly 69 million people, more than any other government or private program. It would do this by gradually but inexorably shifting more of the financial burden of Medicaid to states, in effect, forcing them to cover fewer people and to provide fewer services. Over all, the Senate would reduce federal spending by about $1 trillion over 10 years and use almost that much to cut taxes for rich families and health care companies.

In the days ahead, while the Congressional Budget Office totes up the bill’s cost, and before a floor vote, some Republicans, President Trump included, might be tempted to see the Senate bill as an improvement over the draconian House measure passed in May that would take insurance away from 23 million people. Mr. Trump previously expressed the hope that the Senate version would be less brutal. It isn’t. True, Mr. McConnell and his colleagues have made a few superficial improvements; the rollback of Obamacare’s intended expansion of Medicaid would proceed more slowly than under the House’s timetable. But the long-term damage might be worse. That is because the Senate bill would cap federal spending on Medicaid on a per-person basis. Currently, federal spending varies from year to year based on demand for medical services and the cost of care. Starting in 2025, the cap would be allowed to increase at the rate of inflation in the economy. But the overall inflation rate has typically been much lower than the inflation rate for medical services; in 2016, the overall inflation rate was 1.3 percent, whereas medical costs increased by 3.8 percent. Over time, this would means states will get a lot less money than they do under current law. The inevitable shrinkage in Medicaid will be particularly devastating to older Americans. Contrary to what many people think, the program does not just benefit the poor. Many middle-class seniors depend on it after they have exhausted their savings. Medicaid pays for two-thirds of the people in nursing homes. The disabled and parents who have children with learning disabilities also rely on Medicaid. The program covers nearly half of all births in the country. And in recent years, it has played a very important role in dealing with the opioid epidemic, especially in states like Kentucky, Massachusetts, Maryland, Ohio and West Virginia. Medicaid pays between 35 percent and 50 percent of the cost of medication-assisted addiction treatment, according to two professors, one from Harvard and one from New York University.

Like its House counterpart, the Senate bill would also hurt millions of non-Medicaid beneficiaries of Obamacare, those who buy insurance on federal and state marketplaces. It would greatly reduce federal subsidies that help low-income and middle-income families buy health coverage, while allowing insurers to increase deductibles, forcing people to pay more for medical services. It would let states waive rules that now require insurers to cover essential health services like maternity care, cancer treatment and mental health care, which is likely to happen because this will be the only way that states can lower premiums. In sum, it will make health insurance more expensive and less useful, to the great misfortune of the poor, elderly and sick.

Mr. McConnell seems determined to steamroll this travesty through the Senate before July 4, despite complaints by conservatives and moderates. Expect him and his colleagues to try to buy support of wavering lawmakers by offering sweeteners like a few billion dollars for addiction treatment and some extra cash for states with high medical costs. Republican senators like Susan Collins of Maine, Lisa Murkowski of Alaska, Shelley Moore Capito of West Virginia, Rob Portman of Ohio and Dean Heller of Nevada ought not to fall for these cheap gimmicks. Instead, they should vote no on a bill that will take a devastating toll on millions of Americans and that no amount of tinkering around the edges can make better.