WASHINGTON (AP) — The Biden administration is taking a victory lap after federal officials signed agreements with pharmaceutical companies to lower prices on 10 of the most popular and expensive Medicare drugs, but provided few immediate details on the new prices older Americans will have to pay when they fill those prescriptions.

White House officials said Wednesday night they expected the new prices to save U.S. taxpayers $6 billion, while older Americans could save about $1.5 billion on their medications. But those projections were based on outdated estimates, and the administration did not provide details on how it arrived at those figures.

Still, the renegotiated prices – which were not yet known to the public as of early Thursday morning – will impact the prices of drugs taken by millions of older Americans to treat diabetes and blood cancer and prevent heart failure and blood clots.

The drugs include the blood thinners Xarelto and Eliquis and the diabetes drugs Jardiance and Januvia. Medicare spent $50 billion last year on the cost of these drugs.

It’s a milestone for the Medicare program, which provides health insurance to more than 67 million elderly and disabled Americans. For decades, the federal government was prohibited from negotiating with pharmaceutical companies over the prices of their drugs, even though it’s a routine process for private insurers.

“That meant that pharmaceutical companies could essentially charge whatever price they wanted for life-saving treatments that people depend on, and all Americans paid the price for that,” White House adviser Neera Tanden told reporters on a conference call Wednesday evening.

The drug deals will become a central issue in Vice President Kamala Harris’ presidential campaign, especially since she cast the deciding vote to pass the bill. She will announce drug prices alongside President Joe Biden on Thursday, their first joint appearance since she replaced him at the top of the Democratic ticket. Both have struggled to convince voters that costs will fall after years of above-average inflation.

The couple last appeared together in public to welcome Americans imprisoned in Russia who were released earlier this month as part of a large-scale prisoner exchange.

Powerful drug companies tried unsuccessfully to file lawsuits to stop the negotiations, which took effect in 2022 when a Democratic-controlled Congress passed the Inflation Reduction Act, which overhauled several Medicare prescription rules. But executives at those companies have also indicated on quarterly earnings calls in recent weeks that they do not expect the negotiations to impact their bottom line.

The Centers for Medicare and Medicaid Services, which oversaw the negotiations, is expected to announce the final drug prices later Thursday. The new prices will not take effect until 2026. Next year, the Department of Health and Human Services may select another 15 drugs for price negotiations.

Before drug prices were finalized, the Congressional Budget Office estimated that the negotiations could save the federal government $25 billion in 2031.

The official event will take place one day before Harris unveils part of her economic program in North Carolina on Friday, where she plans to present further measures to help reduce the costs of the middle class and increase their incomes.