At Wednesday night's debate, the six top 2020 Democratic candidates were asked whether the one of them with the most delegates at the end of the presidential primary process should be the nominee -- even if that person didn't have a majority of the delegates.

Five said no. One -- Bernie Sanders -- said yes. Or, more accurately, said this: "Well, the process includes 500 super delegates on the second ballot. So I think that the will of the people should prevail, yes. The person who has the most votes should become the nominee."

Which makes sense. As I noted earlier this week, it is VERY likely that Sanders -- if the race stays, roughly, on its current trajectory --. (Roughly one-third of the total delegates will be doled out March 3 -- and Sanders is well-positioned to win or place second in several states with the largest number of delegates).

Now, if Sanders wins 1,991 delegates or more, then all of this contested convention stuff is moot. (There are available, making 1,991 a simple majority.)

But if he comes up short of that magic number while still leading in the overall delegate count -- an increasingly likely scenario given the continued size of the field and the rules of -- then Democrats could be faced with a nightmare scenario: A contested convention in which Sanders might not wind up as the nominee after multiple ballots.

Here's how it happens:

1) No one wins a majority of the 3,979 delegates before the convention.

2) The first ballot -- in which only pledged delegates that were won in primaries and caucuses are allowed to vote -- doesn't produce a nominee.

3) The second ballot is cast, where superdelegates -- -- are allowed to vote.

4) A candidate with fewer pledged delegates than Sanders secures a majority of all delegates based on support from superdelegates.

That would, quite literally, trigger a cataclysm within the party.

Following the 2016 election, Sanders and his allies fought to drastically reduce the power of superdelegates in the nominating process under the belief that overwhelming superdelegate support for Hillary Clinton made it virtually impossible for the Vermont senator to win despite his repeated success at the ballot box.

"Today is a historic day for our party," at the time of the rule change. "We passed major reforms that will not only put our next presidential nominee in the strongest position possible, but will help us elect Democrats up and down the ballot, across the country. These reforms will help grow our party, unite Democrats, and restore voters' trust by making our 2020 nominating process the most inclusive and transparent in our history."

Which sounds good! But the realities of this election -- a wide field of credible challengers, and two free-spending billionaires in Michael Bloomberg and Tom Steyer -- have now created a scenario where it is at least possible that superdelegate votes again decide the identity of the Democratic nominee.

What's clear is that both sides are hunkering down in their positions at the moment. Sanders has no incentive to budge, given the likelihood he ends with a plurality of the delegates in the race. And the forces arguing against Sanders got a major boost on Thursday, when former Senate Majority Leader Harry Reid (Nevada) rejected the idea of handing the nomination to whoever wins the most delegates in the nomination fight.

"I don't think that anybody -- Bernie Sanders or anyone else -- should simply get the nomination because they have 30% of the delegates and no one else has that many,". "We have to let the system work its way out. I do not believe anyone should get the nomination unless they have 50-plus-one."

On the other hand, as David Plouffe, Barack Obama's 2008 presidential campaign manager, :

"It's possible we are going to have somebody that doesn't have a majority of the pledged delegates. I believe that whoever is the plurality leader unless literally it's a delegate or two ... but even if someone has a 50 or 100 [vote lead] ... we're really going to take the nomination away from them in Milwaukee? I'm not sure the party recovers from that for decades."

So, yeah. Rock and a hard place. Scylla and Charybdis. All those cliches. In short: Democrats' absolute worst-case-scenario for 2020 isn't so far-fetched. And no one knows what to do about it.