LAS VEGAS — One of President Biden’s promises to America’s seniors when he first campaigned for the Oval Office was this: They will pay less for health care.

So on Wednesday, with the announcement of a possible re-election drawing ever closer, the president traveled to Las Vegas to show off that millions of seniors would save on their medications thanks to the health legislation he pushed through last year.

Thanks to the Inflation Reduction Act, he said, seniors will no longer have to pay copays for some recommended vaccines like shingles and tetanus, saving them an average of $70 each year in the future.

“For seniors on a fixed income who often need expensive medications to stay healthy, the ongoing question is whether they can take the medications and pay the bills without giving up important elements of their lives,” Biden told an audience at the University of Nevada, Las Vegas.

“It’s not just his health,” he said. “This is about your dignity. It’s about your safety.”

In the 2020 election, Biden he fell short among people 65 and older former President Donald J. Trump, 48 percent to 52 percent. The president and his advisers hope to increase their support among that group in 2024, arguing that his financial and medical security will be better protected with Biden in office.

The centerpiece of that argument so far has been the fate of the main government retirement programs, Social Security and Medicare. Biden has been aggressive in seizing on proposals from a handful of Republican politicians to argue that the party would jeopardize popular agendas.

He said it Wednesday, standing in front of a sign at the University of Nevada that read “Reducing costs for American families.” The president recalled his State of the Union address this year, when several Republican lawmakers called him a liar for claiming they wanted to cut social safety net programs.

“I hope it’s true,” he said, noting that lawmakers were being filmed denying any interest in hurting Medicare and Social Security. “But I’ll believe it when I see it,” she said.

Beyond that issue, though, the administration argues that older Americans will also be appreciative of the president’s efforts to keep costs down, especially when it comes to his drugs, at a time when prices have risen sharply.

In addition to average savings of $70 on vaccines, White House officials said Wednesday that seniors across the country would benefit from provisions of the Cut Inflation Act that penalize pharmaceutical companies when they increase the cost. of a drug faster than inflation.

Officials said 27 specialty drugs recently met that criteria and their makers will be required to reimburse the federal government for the extra costs. Administration officials said older Americans could see some savings down the road as drug companies keep prices lower to avoid having to pay rebates.

“Some people with traditional Medicare or managed care Medicare can save starting in a matter of weeks,” Health and Human Services Secretary Xavier Becerra told reporters before the president’s appearance.

Biden also highlighted the impact his health care actions have had on the cost of insulin, which is a common — and often expensive — medication for many older people with diabetes.

The president’s health care law limits the price of insulin to $35 a month for seniors, and Mr. Biden has persuaded two of the three largest drugmakers to lower costs for younger people who need insulin. Eli Lilly announced this month that it would limit out-of-pocket costs for insulin to the same $35. Novo Nordisk said it would cut the cost of its insulin drug by 75 percent.

Focusing on medical costs for the elderly has been on Mr. Biden’s agenda since before he became president. His campaign website said under the headline “The Biden Plan for Older Americans” that seniors in the United States “deserve to retire with dignity, able to pay their prescriptions and with access to affordable long-term care and quality”.

But his political ambitions are now part of a political effort to win back part of that demographic that has trended toward Republicans as the average age of people living in the country rises each year.

A group of about two dozen Republican lawmakers is pushing legislation to repeal the Inflation Reduction Act, a move that White House officials and the president have seized on. Biden wants to make his Republican rival in the White House, whoever she turns out to be, pay for a repeal effort by suggesting it will hurt seniors.

In a statement last month, the White House said that efforts to repeal the law would “return tens of billions of dollars in subsidies to Big Pharma, increase the prices of prescription drugs for seniors, and increase taxes on approximately 14.5 million people, all while increasing the deficit.

Mr. Biden’s visit to Las Vegas comes just weeks before he is expected to announce that he is running for a second term. Nevada is a critical swing state that Democrats need in their column if they want to retain control of the White House for another four years. In 2020, Biden carried the state with 50.06 percent of the vote, to Trump’s 47.67 percent.

Wednesday’s speech took place at the William F. Harrah College of Hospitality, a nod to the extremely powerful service unions in Las Vegas and a major Democratic constituency.