He is likely to be succeeded as chairman by Senator Charles E. Grassley, an Iowa Republican who is more of a populist on health policy. In 2015, he and Senator Ron Wyden, Democrat of Oregon, issued a blistering report on their 18-month investigation of the high prices charged by Gilead Sciences for two hepatitis C drugs.

Mr. Grassley has long supported allowing importation of prescription drugs from Canada — anathema to the industry. He wrote the provisions of federal law that require drug companies to disclose the payments they make to doctors for research, consulting, speaking, travel and entertainment. Mr. Grassley is also the foremost champion of whistle-blower laws, under which drug companies have paid billions of dollars to resolve allegations that they defrauded the government or engaged in illegal marketing practices.

The challenges facing the industry were laid out in stark terms this month by Covington & Burling, a Washington law firm that has been advising pharmaceutical companies for more than 75 years.

Rujul Desai, a lawyer, said in a webinar that the firm had done “war-gaming exercises” with senior drug company executives to prepare them for possible congressional investigations and hearings on drug prices. The goal, he said, is to help clients “communicate the value of their innovative medicines.”

One of his colleagues at Covington, Jennifer L. Plitsch, explained how the government could try to use existing laws to force a reduction in the prices of drugs developed with the help of taxpayer funds.

The government has rarely used this authority, Ms. Plitsch said, but that could change. “It is,” she said, “a very easy sound bite for price control advocates: Why should American taxpayers both contribute to drug development and then pay the highest prices in the world as patients?”

She suggested how drug companies could answer that argument: “The sound bite is misleading and simplistic. The proposal would chill innovation and hurt patients. A vast majority of the investment in drug development comes from private industry, not the government.”