House and Senate negotiators thrashing out differences over a major tax bill are likely to eliminate the insurance coverage mandate at the heart of the Affordable Care Act, lawmakers say. But a deal struck by Senate Republican leaders and Senator Susan Collins of Maine to mitigate the effect of the repeal has been all but rejected by House Republicans, potentially jeopardizing Ms. Collins’s final yes vote.

All the talk about killing the Affordable Care Act this year apparently has not sent Californians running from Covered California, the state’s health insurance exchange.

In another example of the blurring boundaries in the health care industry, UnitedHealth Group, one of the nation’s largest insurers, said on Wednesday that it is buying a large physician group to add to its existing roster of 30,000 doctors.

U.S. health spending rose to $3.3 trillion in 2016, but the pace slowed compared to the previous two years as demand for drugs, hospital care and physician services weakened, according to a federal study released Wednesday.

The nation's five largest insurers are increasingly dependent on government programs such as Medicare and Medicaid for growth in enrollment, revenue and profits, according to a new Health Affairs study.

CVS Health said on Sunday that it had agreed to buy Aetna for about $69 billion in a deal that would combine the drugstore giant with one of the biggest health insurers in the United States and has the potential to reshape the nation’s health care industry.