Mayor Pete and Andrew Yang have both totally overperformed. Photo: Justin Sullivan/Getty Images

2019 has been a momentous year when it comes to the “invisible primary” of the 2020 Democratic presidential nominating contest. As the year draws to a close, let’s assess the biggest surprises we’ve seen so far in the competition to choose a challenger to Donald Trump.

Biden’s Resilience

Early front-runner Joe Biden has been a sitting duck for so long that his avoidance of a long-awaited swoon in public support has been a boost to his already formidable reputation for electability. His polling average among the Democratic field at the beginning of 2019, according to RealClearPolitics, was 27 percent. At the end of 2019, it is 27.8 percent. During 2019, Biden has undergone multiple threats to his candidacy, most notably the blow from Kamala Harris (since departed from the contest) in the first candidate debate highlighting his history of opposition to judicially ordered school-desegregation efforts, which was perfectly designed to expose his weaknesses. The year ended with Republican efforts to turn the impeachment trial of Donald Trump into a countertrial of Joe and Hunter Biden.

Biden’s resilience is often attributed to Democratic primary voters’ obsession with electability, reinforced by his durable support from nonwhite and elderly white voters who fear a Trump victory more than they hope for some hypothetical progressive administration. The fact that rivals have their own challenges matters as well. Sometimes it simply seems that Biden is defying gravity. But the fact that he ended 2019 as the Democratic front-runner is a surprise to many observers, myself included.

Bernie’s Resurgence

If one late-septuagenarian candidate’s steady performance in the polls has been a surprise, another’s revival from a dip has been equally surprising.

According to RealClearPolitics’ polling averages, Bernie Sanders was the preferred candidate of 17 percent of Democratic primary voters on January 1, 2019. Now he’s at 19.3 percent. But as recently as October 5, he was at 14.3 percent, trailing Elizabeth Warren nearly everywhere. And he had just suffered a heart attack that made all sorts of friends and enemies wonder if he was done.

Now nobody blanches when center-right analyst Sean Trende paints a scenario for a Sanders nomination victory:

By mid-February most of the field will have dropped out, and where their share of the electorate goes will likely prove crucial. Perhaps more importantly, Sanders may have won the two marquee early contests and thus will have some momentum heading into Nevada. He currently trails there, but the race is underpolled and he very nearly won in 2016.

If Sanders were to sweep the first three contests, he would become very difficult to beat.

He’s not going away, and more to the point, Elizabeth Warren’s candidacy has not marginalized his, as you might have expected.

Pete’s Viability

In the vast initial 2020 Democratic presidential field, it was by no means clear that the 37-year-old mayor of South Bend was going to become a top-tier candidate. In March, he was well below one percent in candidate preferences. Now he is at 8.3 percent and, more importantly, leads the polling averages in Iowa and is a close second in New Hampshire.

Buttigieg is not doing so well in states that vote later in the process, where nonwhite voters — among whom he has very low support — are predominant. But presumably he will get a fresh look if he survives the first few contests. In the meantime, you have to figure that he has benefited from a series of solid debate performances, fundraising support from fellow LGBTQ folk, and positive vibes from opinion leaders who fear Biden, Sanders, and Warren are too old to win.

Nonwhite Voters Don’t Prefer Nonwhite Candidates

The decline in support for African-American and Latino candidates has been a big deal, too, as my colleague Eric Levitz has explained:

Judging by recent national polls, if only African-Americans were allowed to vote in the Democratic primary, the top three contenders would be Joe Biden, Bernie Sanders, and Elizabeth Warren — the same three candidates preferred by the Democratic electorate as a whole. Meanwhile, black Democrats’ overwhelming favorite among that trio is also the race’s clear front-runner. If Joe Biden retains his current standing, then the Democrats’ 2020 nominee will better reflect the preferences of black Democrats than those of white ones: In Quinnipiac’s most recent poll, the former vice-president boasts only 21 percent support among white primary-goers, but a whopping 51 percent support among African-Americans.

Latino Democratic voters, according to a November survey, vastly prefer Biden and Sanders to Julián Castro.

It may represent a combination of Biden’s electability rationale and Sanders’s powerful appeal to younger voters, but any way you look at it, nonwhite voters have undercut nonwhite candidates. That’s a surprise.

Yang Is Doing Better Than Many Conventional Candidates

There have been a number of conventionally strong candidates who have dropped out or seem to be heading in that direction. Among them are Montana governor Steve Bullock, Colorado governor John Hickenlooper, and early Texas sensation Beto O’Rourke. And there are other barely surviving presidential prospects with pretty good résumés, such as Senators Cory Booker and Michael Bennet and Representatives Tulsi Gabbard and John Delaney.

Andrew Yang has consistently outperformed them all. He has qualified for all six presidential candidate debates held so far and is currently tied with Amy Klobuchar in the RealClearPolitics’ national polling averages.

Yes, Yang has some interesting signature policy proposals, and yes, he’s done well intermittently in debates, and yes, his fundraising totals have been impressive, and yes, he’s got a social-media Gang spreading his word. But still, his campaign is overperforming any reasonable expectations.

What surprises are still ahead? Hard to say, though when caucus and primary voters upend expectations, the ripples in the tide tend to spread and things can get very weird.