Sanders is by far the most successful presidential candidate to advocate for a single-payer health system.

Although many Democrats, including President Obama, have expressed support for the concept of a system resembling that of most other western countries, the political realities in the U.S. tend to force even very liberal politicians to put aside the dream of single-payer in favor of a policy that maintains the country’s vast, for-profit health insurance industry. Hence, the Affordable Care Act.

The Democratic presidential primary, however, suggested that there was a much greater appetite for a fundamental reform of the health care system among Democrats and liberal-leaning independents than party leaders likely realized.

Hillary Clinton was repeatedly put on the defensive over her lack of support for a single-payer solution. As a result, her position on health care gradually shifted to the left throughout the primary. Most notably, she announced support for allowing people to opt into Medicare at age 55 and said she would support the creation of a “public option” government-run insurance program that would compete with private plans.

In Sanders’ own state, Vermont, the Democratic governor and state legislators explored setting up a single-payer system shortly after the implementation of the ACA in 2014. However, that effort was abandoned at the end of that year, when Gov. Peter Shumlin conceded that the state didn’t have the funds necessary to put such a program in place.

ColoradoCare seeks to address the financing issue head on by levying a tax on employees and companies. If approved, the plan is anticipated to cost $38 billion a year.

Obviously, that price tag is enough to scare away many would-be sympathizers of single-payer and has divided Democrats in Colorado. Democratic Gov. John Hickenlooper is opposed.

Supporters of the plan, however, point out that the big tax increase will be offset by the elimination of the thousands of dollars a year in private health care costs that currently burden individuals and businesses.

A poll conducted in June found majority support for the plan among Colorado voters.