Expanding Medicare, to varying degrees, has become more or less the standard position for Democratic presidential hopefuls. In the early field of Kamala Harris, Cory Booker, Elizabeth Warren, Kirsten Gillibrand, and Bernie Sanders, all back a Medicare for all sort of plan. Julian Castro agrees, saying in his announcement speech that "it's time for Medicare for All."
Not all of the candidates have released detailed policy papers on what they want to see and how they'd get there, but Medicare expansion to one degree or another is at the top of the list. (Daily Kos has reached out to all of the campaigns and requested policy proposals.) Amy Klobuchar wants to start by lowering the eligibility age to 55. For some, including South Bend, Indiana, Mayor Pete Buttigieg, it means keeping some form of private insurance, even though Medicare for all is "the right place for us to head as a country."
That's kind of where one of the latest entrants, Beto O'Rourke, lands. He's not really for single-payer Medicare for all, but more of a hybrid kind of public option idea that some House Democrats have put forward, Medicare for America. That's essentially going back to the progressive position in 2009-10, of a public option on the Affordable Care Act exchanges available off-exchange as well, but maintaining employer-sponsored insurance if people choose to.
The guy from Colorado lags behind the field. Former Gov. John Hickenlooper has almost taken himself out of the running by stating that he thinks he can solve everything by just sitting down for a heart-to-heart chat with Mitch McConnell. He says he "probably would oppose Medicare-for-all just because there are over 150 million people, Americans who have some form of private insurance through their business, and the vast majority of them are happy with that." He shouldn't be so sure. Polling has shown that people with employer-based insurance are more than open to the idea of Medicare for all. They're not that much in love with the increasingly higher deductibles and out-of-pocket costs they're hit with. It almost seems like Hickenlooper just hasn't been paying all that much attention to anything at the national level.
There is at least basic agreement among Democrats that we have not reformed. The ACA didn't do the trick entirely, largely because it's been too easy for Republicans to sabotage, from the Congress to Trump to the courts. Differentiating among the candidates is going to come down in part to who learned that lesson, and what they intend to do about it.