On a day when the top tier of Democrats are getting ready to debate for the last time before the Iowa Caucus, U.S. Sen. Michael Bennet’s campaign was talking about an issue hot in his home state, a public option insurance program.

Gov. Jared Polis and fellow Democrats in the General Assembly are working a state plan to provide insurance that competes with private insurance and, ideally, pulls down rates. With hospitals, insurers and businesses watching closely, the struggle is expected to be one of the biggest fights at the Capitol before the legislative session ends on May 6.

Bennet for America on Tuesday unveiled an ad pitching a national public option supported by the candidate called Medicare X. He details the proposal on his website.

The idea isn’t new to the Colorado senator. In 2017, he and Sen. Tim Kaine of Virginia, who was Hillary Clinton’s running mate four years ago, introduced legislation to create the government-run health insurance plan that would have allowed anyone to buy coverage under Medicare, the federal program that covers the elderly, or opt to keep the coverage they have now through their employer.

The proposal is Bennet’s campaign is a counter to Medicare for All, which would unravel employer-based insurance for a massive government program, which has been supported by more progressive candidates vying for the White House, led by Sens. Elizabeth Warren of Massachusetts and Bernie Sanders of Vermont. The idea has faded on the trail the past few weeks, but Bennet has argued it’s an expensive, chaotic proposal that’s not realistic.

“My own family wants to make the choice about what’s right for our family, and I believe that’s true for almost all the families in America,” Bennet says in the ad. “Under my plan, every single person who hates their private insurance is now going to be able to get off of it and get on a public option.”

Bennet posted the video on Twitter on Tuesday.