Sen. Bernie Sanders (I-Vt.) this week endorsed a Colorado ballot measure that would create single-payer healthcare in the state, urging his supporters to rally around the amendment and stating, "If that proposal can win in Colorado, I believe that idea will spread around the country."

"It is absurd, it is beyond belief, that here in America we remain the only major country on earth not to guarantee healthcare to all people," Sanders said at an event in Vermont on Wednesday, where he offered his official endorsement.

As the Denver Post reports, Colorado Amendment 69—known colloquially as ColoradoCare—would create a universal healthcare system funded by payroll taxes that would largely replace private health insurance. People could still choose to keep their own, although they would still be required to pay the tax.

Support for the measure from Sanders carries a lot of political weight; not only was universal healthcare a cornerstone of his presidential campaign—one of the signature issues that endeared him to progressive voters—but he also won the Colorado caucus in March.

Owen Perkins, a spokesperson for the ColoradoCareYES campaign, said in a statement this week that "It's hard to imagine a figure whose support of ColoradoCare is more meaningful than Senator Sanders."

"No one has done more to elevate the idea of Medicare-for-all in the United States in recent years, and by bringing the notion of universal healthcare into stadiums, auditoriums, town halls, and living rooms throughout the country, Senator Sanders has helped create the ideal environment for passing ColoradoCare," Perkins said.

If Colorado approves the amendment, it will be the first state in the nation to implement single-payer healthcare. And as Health Care for All Colorado executive director Donna Smith told Common Dreams in November, that could have national implications, because "we are not relying on the elected officials to advance universal healthcare."

"This may be a way for other states to learn from our work in Colorado and also pursue single-payer reform at the ballot as a way to overcome some of the political inertia that settles in when so many powerful, monied interests hold court over the legislative process," Smith said at the time. "The ballot measure...is about much more than achieving healthcare justice. It is also about citizens coming together and using the democratic process to successfully achieve healthcare justice."