The nation’s largest senior advocacy group, AARP, is launching a campaign to block congressional efforts to turn Medicare into a voucher system.

Laura Polacheck, the communications director for AARP Utah, says with GOP control of the White House and both chambers of Congress, House Speaker Paul Ryan’s proposal to privatize the government-run health program for people with disabilities and those age 65 and older stands a good chance of being signed into law.

“People understand what Medicare is and how important it is to their lives, and we want them to understand it’s at risk, and that they need to take action immediately so that their respective members of Congress understand they’re concerned,” she said.

Ryan Proposal Would Raise Costs Says AARP

To reduce federal spending, Ryan has proposed changing Medicare from a single-payer system, where the program pays for health-care directly, to a system where seniors can opt for private insurance using government vouchers. Polacheck argues the move would increase health-care costs and risks, both for current and future retirees.

Polacheck says AARP staff and volunteers will remind members of Congress that Ryan’s proposal would put more than 300,000 Utah seniors’ benefits at risk, as well as the benefits of over 400,000 workers currently paying into the system and set to transition to Medicare over the next 15 years.

“We believe Medicare is an earned benefit and that it should remain as an earned benefit, with people being able to rely on coverage that it guarantees when they’ve paid in it during their working life,” she added.

She also adds that the group will use broadcast and social media to urge Congress to keep President Trump’s promises. During the election campaign, then-candidate Trump said he would protect Social Security and Medicare, which he characterized as deals made “a long time ago.”