WASHINGTON — It's entirely possible that neither Joe Biden nor Bernie Sanders will be the Democratic presidential nominee. But right now, the two men best represent the central ideological fight in the 2020 Democratic race.

It's Biden-ism versus Sanders-ism.

Here was Biden-ism on display Saturday: "As long as Donald Trump is in the White House, none of these critical things will get done," the former vice president said during his rally in Philadelphia. "So if you want to know what the first and most important plank in my climate proposal for the America is — beat Trump."

And here was Sanders-ism on Sunday: "Beating Trump is not good enough. You've got to beat the fossil fuel industry. You have to take on all of those forces of the status quo, who do not want to move this country to energy efficiency and sustainable energies," Sanders said on "Meet the Press" yesterday.

More Sanders: "Our campaign has a different goal. It's to transform this country. And we're taking on the entire establishment."

It's restoration versus revolution, as we've written before.

By the way, did anyone else notice that Sanders — when he talked about taking on "the entire establishment" — included figures in the Democratic Party? Of course, you can easily see how a Biden-versus-Bernie fight could allow another 2020 Dem to break through next year.

And you can also see how Democrats might ultimately prefer a middle ground in Biden-ism versus Sanders-ism — someone who represents more than a restoration, but also someone who doesn't want a revolution, including inside the Democratic Party.

But, for now, this is the main fight within the 2020 Democratic contest.

A bigger field helps Biden and Bernie

While Democrats could end up nominating someone who isn't Biden or Sanders, the enormous size of the Dem field benefits the two frontrunners.

"In his landmark book The Paradox of Choice, psychologist Barry Schwartz offered a counterintuitive argument: People claim they want more choices in life, but when they get them, they become paralyzed in their decision-making," National Journal's Josh Kraushaar writes.

And that paralysis helps the more established brands.

The Washington Post's Dan Balz adds that the sheer size also might help the frontrunners during the debates, making it difficult for other candidates to break through.

"The size of the field ... will limit the value of these early encounters, which will have to be held on consecutive nights to accommodate all of the candidates expected to qualify."

Tweet of the day

No one is unhappy (“look, honey they have grilled cheese for the kids and I can get a salad), but no one walks away thinking that was an amazing meal or experience. It’s not risky, but it’s also not totally satisfying either. (2/2) — amy walter (@amyewalter) May 19, 2019

Why Justin Amash's tweet was so significant

On Saturday, Republican Rep. Justin Amash of Michigan fired off this tweet as part of a lengthy thread about the Mueller report.

“Here are my principal conclusions:

Attorney General Barr has deliberately misrepresented Mueller’s report. President Trump has engaged in impeachable conduct. Partisanship has eroded our system of checks and balances. Few members of Congress have read the report.”

And in doing so, he became the first Republican lawmaker to say that Trump has potentially engaged in impeachable conduct.

But Amash's tweet is even more significant than that, because there’s plenty of evidence that his case is factually correct:

As we've said before, Barr's initial summary of Mueller's conclusions omitted key material, including the special counsel's statement that Congress could decide whether Trump committed obstruction of justice. Mueller listed 10 episodes of Trump potentially obstructing justice. As he stated, "[W]hile this report does not conclude that the President committed a crime, it also does not exonerate him." It's pretty evident that congressional Republicans have ceded their constitutional power to be a check and balance on the president. Raise your hand if you're Trump or a member of Congress and have actually read the full report.

Not surprisingly, Trump fired back at Amash yesterday, tweeting:

“Never a fan of @justinamash, a total lightweight who opposes me and some of our great Republican ideas and policies just for the sake of getting his name out there through controversy. If he actually read the biased Mueller Report, “composed” by 18 Angry Dems who hated Trump….

“…he would see that it was nevertheless strong on NO COLLUSION and, ultimately, NO OBSTRUCTION...Anyway, how do you Obstruct when there is no crime and, in fact, the crimes were committed by the other side? Justin is a loser who sadly plays right into our opponents hands!”

2020 Vision: The president in Pennsylvania

At 7:00 pm ET tonight, President Trump holds a rally in Montoursville, Pa. — which is outside of Williamsport. That comes after reports that his reelection campaign is increasingly worried about losing ground in the Rust Belt states — Pennsylvania, Michigan and Wisconsin —that delivered his 2016 win.

POLITICO writes this morning that Trump campaign staff have “rushed to the aid of languishing state Republican Party machines and have raised concerns that a potential GOP Senate candidate in Michigan could hurt the president’s prospects there. They are also scrutinizing the map for opportunities to fire up his base in the trio of states.”

On the campaign trail today

Beto O'Rourke is in Iowa, where he tours flood damage and stumps in Davenport... Bernie Sanders holds a town hall in Alabama... And John Hickenlooper, in Chicago, delivers a foreign-policy address.

Data Download: The number of the day is… $171,000, $20,920, and $17,409

$171,000, $20,920, and $17,409.

That was the median family wealth for white families, Hispanic families and black families, respectively, in 2016, according to the Urban Institute.

And the huge gap between whites and minority groups is becoming one of the signature issues of the 2020 primary, with most candidates explicitly describing detailed agendas to address it.

Check NBC’s Benjy Sarlin on what some of those plans look like, here.

The Lid: Tea leaves

Don’t miss the pod from Friday, when we checked in on some of the overlap between the Tea Party and the Trump coalition.

ICYMI: News clips you shouldn’t miss

Pete Buttigieg went on the attack against some Fox News hosts while participating in a Fox town hall last night.

Mike Memoli gives his take on Biden’s Saturday kickoff rally.

Elizabeth Warren is reaching out to black female voters — and it may be working.

Florida Gov. Ron DeSantis says that Trump told him undocumented immigrants would not be shipped to his state.

Don’t miss this deep look from the New York Times on how exploitative loans victimized taxi drivers and caused a crisis in the industry.

Trump agenda: Here in Youngstown

The New York Times surveys the political scene in Youngstown.

Here’s what Jared Kushner is hoping for with an “economic workshop” on the Middle East peace drive.

States are going their own way on environmental protections.

Trump says he has some concerns that E-Verify could be burdensome for some employers.

2020: The Jimmy Carter renaissance

Kamala Harris has a plan to address the gender pay gap.

Kirsten Gillibrand says she wouldn’t detain migrants at all.

Tulsi Gabbard is using the phrase “fake news” to describe a Daily Beast report alleging that her campaign is being backed by Russian sympathizers.

POLITICO asks: “Is Andrew Yang for real?”

Jimmy Carter is having a moment.