The Biden administration on Thursday unveiled the results of landmark drug price negotiations between Medicare and pharmaceutical companies, allowing President Biden and Vice President Kamala Harris to cast themselves as confronting the drug industry on behalf of older Americans at a critical moment in the presidential campaign.

The negotiated prices, which take effect in 2026, are expected to save billions of dollars for Medicare, which is funded by taxpayers. But they will lead to direct out-of-pocket savings for only a subset of the millions of older Americans who take the drugs subject to negotiations.

Other provisions of the law that created the drug negotiation program, such as capping patients’ expenses for insulin and their yearly out-of-pocket drug costs, will do more to save older Americans money at the pharmacy counter.

The 10 drugs subject to negotiations include widely used blood thinners and arthritis medications. Had the new prices been in effect last year, administration officials said, Medicare would have saved $6 billion, which would have reduced its spending on those drugs by 22 percent.

“This is a fight all of us have been fighting for a long time: taking on Big Pharma,” Mr. Biden said at an event in Maryland celebrating the announcement, where he and Ms. Harris had their first joint public appearance since she took over the Democratic presidential ticket.

The negotiations, a longtime aspiration of Democrats, are the first that the federal government has directly conducted with drugmakers on behalf of Medicare beneficiaries. Mr. Biden on Thursday recalled working on legislation as a senator in the 1970s that would have allowed Medicare to negotiate prices directly.