President Trump will break another promise Friday afternoon when he unveils his plan for lowering the cost of prescription drugs, backing off his campaign trial pledge to use the government's power to negotiate them for Medicare.

And that means he's selling out to the drug companies, according to none other than Trump himself.

Here's what to expect from Trump's announcement, per The Post's Carolyn Y. Johnson:

The plan would seek to improve negotiation within the Medicare program, but not by using the government's clout to negotiate for Medicare as Trump has previously proposed. It would create unspecified incentives for lower list prices of drugs and would lower out-of-pocket spending by patients. ...

During his presidential campaign, Trump called for the government to use its clout to negotiate Medicare drug prices, but senior administration officials said he would not call for that change — which is stridently opposed by drug companies. The administration officials did not specify particular policies, but in his budget, Trump proposed changes to Medicare benefits. For example, the budget called for allowing prescription drug plans to have more flexibility to exclude drugs and strike better deals.

The New York Times is also reporting that Trump won't call for Medicare to negotiate drug prices. In other words, it's a half-measure. We don't know exactly what Trump will propose, but it sounds as though it will come up short of what he proposed on the campaign trail.

But Trump didn't just propose the change on the campaign trail; he said those who opposed it were in the pockets of the drug companies — a criticism that could now just as aptly be applied to him.

“We don’t do it,” Trump said in 2016, projecting that such a change could save Medicare $300 billion annually. “Why? Because of the drug companies.”

The White House said in February 2017 that Trump continued to support negotiating Medicare drug prices:

Q: Is he for Medicare negotiating drug prices or not?

Sean SpicerHe's for it, yes. He wants to make — absolutely. The president's clear — I mean when you look at the cost — not just drug cost. The U.S. government has not done — I mean, you look at what other — frankly, the easier way to look at this is what other countries have done — negotiating costs to keep those down.

Trump often spoke more generally about negotiating drug prices in 2017, without specifically citing Medicare.

“The other thing we have to do is create new bidding procedures for the drug industry, because they're getting away with murder,” he said in early January 2017, just before being inaugurated.

After appearing to back off the pledge, he re-upped it again in March 2017: “And remember, we're going to negotiate, and it's going to go to the Senate and back and forth. The end result is going to be wonderful, and it's going to work great. Once this is done, we are also going to work on bringing down the cost of medicine by having a fair and competitive bidding process.”

Around that same time, Rep. Elijah E. Cummings (D-Md.) said he had received personal assurances from Trump that Trump would pursue negotiating drug prices, as reported by the Hill:

Cummings, after sitting down with Trump for roughly an hour in the White House, said the president not only gave his enthusiastic support for Medicare negotiation, he’s also pushing to grant the federal government even broader negotiating powers.

“The president was clearly very much aware what was going on. He understood the issue very well,” Cummings told reporters afterward. “And he felt it was important that we address this issue head-on.”

This isn't the first time Trump has said a position he wound up taking was essentially a sellout to powerful interests. After the mass shooting at a high school in Parkland, Fla., he repeatedly suggested that members of Congress didn't act because they were “afraid” of the National Rifle Association. Trump, it turns out, hasn't pushed for changes that the NRA opposed, after all.

It's one thing to make a promise; it's another to say those who oppose it are in the pockets of powerful interests — and then join them.