An increasingly popular culprit in the debate over high drug prices is the pharmaceutical rebate, the after-the-fact discounts that form the heart of the nation’s arcane — many would say broken — market for prescription drugs.

Now, a growing chorus wants to get rid of them, or at least change the way they are applied after drug companies have already set their prices . Rebates, critics say, have pushed up the list price of brand-name drugs, which consumers are increasingly responsible for paying. Insurers generally get to keep the rebates without passing them along to their members.

Last week, the drug industry’s largest trade group, the Pharmaceutical Research and Manufacturers of America, took aim at the rebate system, proposing a change to the way middlemen handle rebates, and how those companies are paid.

And the Trump administration has taken the first step toward eliminating a “safe-harbor” provision that allows rebates to be paid in Medicare’s Part D drug program without violating federal anti-kickback laws.