Jon Tester (D-MT), ready to consider single payer healthcare.

Sen. Kirsten Gillibrand has become the latest Democrat to endorse Sen. Bernie Sanders' Medicare for All bill, a healthcare reform goal that is quickly become the standard by which Democratic healthcare reform plans are going to be measured.

Sure, you can say that a bunch of the cosponsors so far—Gillibrand, Cory Booker, Kamala Harris, Elizabeth Warren—are doing it because they have to stake out a solid left position for potential 2020 presidential runs. But look at the other Senate Democrats who are cosponsoring so far: Jeff Merkley, Sheldon Whitehouse, Ed Markey, Brian Schatz. Then consider this:

Notably, Sen. Jon Tester (D-Mont.) said last week that Congress should take a "solid look" at single-payer. Activists hailed even those cautious words given Tester represents a red state and has previously been dismissive of the idea that single-payer's time has come. (Tester said "we are so far away" from that debate in both March and June.)

We're not so far away from that debate, and Tester isn't just any red state Democrat. He's one who is up for reelection in 2018. While, seven years after the fact, Republicans still can't agree on any kind of way forward, Democrats are envisioning a path forward, one that really would provide universal health care.

Maybe we can thank Republicans for this. After all, if they'd lifted one finger to make the Affordable Care Act work as intended and worked with Democrats to make the fixes to it that have proven necessary, it would be working well enough and we wouldn't need more reform. As it is, they've done the country a big favor in making single payer healthcare in the United States an accepted and embraced policy discussion for mainstream Democrats. Even the elected ones.