With no clear front-runner for the 2020 Democratic presidential nomination, several prospective candidates are beginning to stir. The process of touching donors and activists has begun, and a Democratic Party message that is beyond simply being anti-Trump is becoming increasingly clear.

The Post’s Paul Waldman recently confirmed the consensus that is forming among 2020 Democratic candidates in support of a single-payer health-care system. I have worried for some time that while Democrats were falling in line with a deceptively simple health-care message, Republicans were stumbling into maintaining a broken Obamacare that they don’t support but cannot generate the political will to replace. Not good.

Beyond the call for a single-payer health-care system, the Democratic candidates appear to be coalescing around a core set of issues that constitute a dangerous lurch to the left.

As I see it, the ante to be in the game as a serious contender for the Democratic nomination will include uniform positions on at least five issues. Specifically, any Democrat who wants to be taken seriously must support a single-payer health-care system, a $15 minimum wage, free college tuition, affirmative support for sanctuary cities along with minimal immigration controls and, finally, a contender must completely embrace Black Lives Matter and engage in a probing courtship with the radical pseudo-group the “antifa.”

The race to be the Democratic nominee for president in 2020 will be a race to the left. The Bernie Sanders agenda has taken root. By the time the Democrats’ nominating process was complete in 2016, Hillary Clinton had become Bernie Sanders-lite. I see the next Democratic nominee as likely to be Sanders on steroids.

Economic polices will consist of government giveaways and anti-business crusades. Social causes will give no quarter to moderate positions, and LGBT special interests, labor unions, global warming fanatics and factions such as Black Lives Matter, along with other grievance industry groups, will face no moderating counterforce. (Disclosure: My firm represents interests in the fossil fuel industry.)

One interesting question is how the antifa will be written into the 2020 script. Maybe it will disintegrate and never achieve critical mass as a political force. The stoners that formed the core of the Occupy movement never had the energy to do anything, but maybe the antifa will do too much and never be viewed as more than an American version of Euro-anarchist soccer hooligans.

But just as the right tries to normalize President Trump, the left will try to normalize the antifa. As the rationalization gets underway, the presidential candidates wanting to distinguish themselves in a crowded field will be temped to show common cause and try to harness the antifa fury. The pandering to come will be nauseating, but nonetheless compelling to watch.

American presidents usually get reelected. And with the Democratic candidates embracing a radical agenda, it would be easy to believe that 2020 could be a modern replay of the 1972 Nixon vs. McGovern race. But I worry that Trump is so unpopular and shows so little capacity for broadening his appeal to the wider electorate that he could be an exception — a la Jimmy Carter in 1980. (I disclose, once again, that I never thought Trump would win in 2016. But here we are.)

Anyway, the Democrats’ lurch to the left is particularly frightening when you think how a candidate with the aforementioned agenda might actually win and set a divided America on a destructive collision course.

Democrats are now captive to the party’s left-wing fringe. Single payer is just the beginning.