In battleground congressional and statehouse districts, the same pattern appeared over and over again this year. At the top of the ticket, Joe Biden won, often handily. Further down the ticket, in contests for seats in the House and state legislatures, Democratic candidates repeatedly lost.

The surge of suburban Democratic voting in 2018 for House and state legislative collapsed in 2020, with Republicans gaining 179 state legislative seats and at least 11 seats in the House of Representatives.

Take the 34th State Senate District in the northwest suburbs of Minneapolis. The district has all the earmarks of an ideal Democratic target in the era of Donald Trump. It has a median household income of $101,644, far higher than the $68,703 national median; it is 86.8 percent white but 49.3 percent of residents over 25 have a college degree, compared with 36 percent nationally.

The 34th is just the kind of upscale, well-educated community that has found the Trump presidency repellent.

At the presidential level, that calculation proved dead right. Biden beat Trump there, carrying what had traditionally been a Republican community by a solid 7.6 percentage points.

But at the state legislative level, it was a different story: Bonnie Westlin, the Democratic-Farmer-Labor candidate for the State Senate, lost to Warren Limmer, the Republican incumbent, by just under 2 percentage points. Westlin was not alone.

As more detailed analyses of the 2020 election emerge, one thing is clear: For millions of voters, a vote against Trump did not mean a vote for the Democratic Party.

In 2018, Democratic gains in congressional and legislative races were clearly the result of animosity to Trump that found expression in voting against Republicans not named Trump — because Trump was on not on the ballot. With Trump on the ballot this year, however, these same voters discovered that they could voice their disapproval of him by voting against his re-election, while returning to their more conservative instincts by voting Republican in the rest of the races.

A spate of recent news stories illustrates the Democratic conundrum.

The headline “How Democrats Suffered Crushing Down-Ballot Losses Across America,” topped the piece my Times colleague Trip Gabriel published on Nov. 28:

Across the country, suburban voters’ disgust with Mr. Trump — the key to Mr. Biden’s election — did not translate into a wide rebuke of other Republicans, as Democrats had expected after the party made significant gains in suburban areas in the 2018 midterm elections. From the top of the party down to the state level, Democratic officials are awakening to the reality that voters may have delivered a one-time verdict on Mr. Trump that does not equal ongoing support for center-left policies.

Or take California, which had been a Democratic gold mine in recent decades. Not only did Republicans win back three of the seven House seats the party lost in 2018, but as Ben Christopher wrote on the nonprofit news site Cal Matters, “the blue wave of 2018 yielded to a red riptide.”

Jeremy B. White elaborated at Politico:

The myth of lock step liberal California took a hit this election. Voters in the deep-blue state rejected a progressive push to reinstate affirmative action, sided with technology companies over organized labor and rejected rent control. They are poised to reject a business tax that had been a decades long priority for labor unions and Democratic leaders.

Liberals, White continued, “thought 2020 was their moment to secure long-desired changes: California’s electorate has become steadily more diverse and Democratic in recent decades, relegating its once-mighty Republican Party to the political margins,” but they “miscalculated. There was no bigger example than voters’ decisive rejection of Proposition 16. The ballot measure would have reinstated affirmative action and directly repudiated what liberals consider a racist chapter of California’s recent past.”

In a major win for the tech giants of the gig economy, California voters defied organized labor and liberal interest groups to approve Proposition 22, exempting such firms as Uber, Lyft, DoorDash and Instacart from requirements that they treat their workers as employees qualifying for benefits and worker protections, rather than as independent contractors.

In Texas, where Democrats were hoping to further capitalize on 2018 victories, the Texas Tribune reported:

Texas Republicans managed to avoid net losses in the state and U.S. House this election cycle in part because voters in key districts showed a willingness to vote Democratic at the top of the ballot and Republican lower down.

I asked Yphtach Lelkes, a political scientist at the University of Pennsylvania, about the increasing centrality of the suburbs in elections. His reply signaled some of the Democrats’ future problems:

As Democrats and Republicans continue to gather strength in high- and low-density areas, respectively, the swing voters will be found in the suburbs. Democrats will have to respond to the more progressive wings of the party but fend off accusations of socialism that may turn off suburban voters. With Trump out of the White House, and with it, his bombastic rhetoric, I expect Republicans will have an easier time with suburban voters than they had over the past four years.

The ambivalence of suburban voters in 2020 — their clear hostility to Trump combined with their reluctance to support Democrats in downballot races — poses a dilemma for Democrats looking for sustained growth in a post-Trump era.

If the 2020 movement in relatively affluent well-educated suburbs away from Democratic voting for legislative and congressional candidates is more than a temporary phenomenon, then maintaining the House majority, as well as having a shot at winning control of the Senate, will prove to be a tough challenge. These jurisdictions are just where Democrats are seeking to strengthen their congressional majority and to win majorities in state legislatures.

Texas provides a case study in the damage suburban defection can inflict on Democrats.

Robert M. Stein, a political scientist at Rice, supplied The Times with data on the top five Republican-held state house districts targeted by Texas Democrats in 2020. The five districts — two in Collin County north of Dallas, two in Tarrant County (Fort Worth) and one in Dallas County — Stein noted, were “predominately white suburban or exurban districts with above average education and income for Texas.”

What happened in these districts on Nov. 3? Biden carried all of them, by an average of 6.5 points, Stein wrote, but all the Democratic challengers for state legislative offices fell short.

The strategic importance to the Democratic Party of converting traditionally Republican voters in the upscale regions of the country at both the federal and state levels is evident in county-level voting data. As the chart below shows, from 2016 to 2020, Democrats continued to hemorrhage votes in low-income, low-education counties, once the base of the party, and to make up for those losses with gains in high-income, high-education counties.

These recent trends are part of a long-term shift in voting patterns. Neil Newhouse, a partner in the Republican polling firm Public Opinion Strategies, provided data to The Times showing that in 1980, Republicans won 76 of the 100 counties with the largest share of college degrees. In 2020, Democrats won 84 of these high education counties.

Similarly, in 1980, Republicans won 91 of the 100 counties with the highest median incomes, and Democrats 9. In 2020, Democrats won 57 of the top income counties and Republicans 43.

In part because of the strength of the affluent wing, there is a growing internal conflict within the Democratic Party between an ascendant and assertive left wing that has gained strength by ousting Democratic incumbents in lower income, majority-minority districts, versus those seeking to win in moderate, more upscale districts with Republican incumbents where voters are more centrist than liberal.

As has become ever more glaringly evident, these two factions hold conflicting views on both policy and strategy.

The progressive wing contends that the Democratic Party needs to take aggressive stands on issues from climate change to immigration, from police reform to massive infrastructure spending, from a minimum wage to strong antitrust regulation. These policy stands are crucial to the mobilization of the young, the poor and, often, Black and Hispanic voters, all of whom are essential to Democratic victories.

The moderate wing argues that for the Democratic Party to expand beyond its urban base, it must appeal to middle-of-the-road voters in purple America who distrust radical change, who support the police — or at least don’t want to defund them — and who prefer cautious steps to expand and improve health care, to reduce inequality and to improve conditions for the working poor. If those moderate voters are alienated, centrists contend, the Democratic Party will stagnate rather than grow.

While still a relatively small cadre, the left wing gained strength in 2020 with the election of Jamaal Bowman and Cori Bush to the House. Both ousted seemingly entrenched Democratic incumbents in majority-minority districts, Eliot Engel in New York and William Lacy Clay in St. Louis. If progressives vote as a bloc, their numbers in both branches of Congress could prove crucial since Democrats will need every vote to pass legislation.

During the campaign, Cori Bush provoked a firestorm of controversy when she tweeted on June 4, “We need to defund the police and make sure that money goes back into the communities that need it,” and on Oct. 20, “If you’re having a bad day, just think of all the social services we’re going to fund after we defund the Pentagon.”

Moderate Democratic candidates have complained bitterly that rhetoric like this receives wide publicity, prompting some voters to believe that the Democratic Party will follow Bush’s suggestions. Republican strategists claim that “defund the police” and socialism have been highly effective when used in negative ads directed against Democratic candidates who in fact repudiated these views.

Looking to the future, the question is how these conflicting interests and trends will affect the outcome of the 2022 off-year elections and the 2024 presidential election.

Marc Hetherington, a political scientist at the University of North Carolina and one of the authors (along with Jonathan Weiler) of “Prius or Pickup?: How the Answers to Four Simple Questions Explain America’s Great Divide,” cites the key role of urban and suburban whites in the 2020 election in Georgia to demonstrate their crucial position in the contemporary Democratic Party.

From 2016 to 2020, Hetherington argued in an email,

there was no marked increase in the percentage of nonwhite voters. The racial composition of the Georgia electorate was about the same in both 2016 and 2020. And, the percentage of African-Americans voting for the Democratic candidate was also about the same.

Instead, Hetherington found,

what appears to have changed the most is the voting behavior of whites. When Trump won Georgia by 5.1 points in 2016, 75 percent of whites voted for him. In 2020, however, that percentage dropped to 69 percent.

The key factor in this shift among white voters, Hetherington contended, was a major change in “the mix of urban, suburban, and rural voters” who turned out in 2020. The preliminary data suggests

that the percentage of voters in Georgia who hailed from rural areas plummeted from 23 percent of the electorate to 14 percent, while the percentage of the electorate from urban areas — a highly Democratic group — increased by five percentage points and the suburban share of the vote increased by four points.

This did not happen because

rural Georgia voters stayed home. The numbers of votes cast in rural counties actually increased between 2016 and 2020. But the numbers of votes cast in more-Democratic friendly urban and suburban areas simply increased by a lot more,” according to Hetherington. “It seems plausible that the increase in Democratic support among whites is because more of those white voters lived in cities and suburbs than in rural areas.

I asked Hetherington whether the future of the Democratic Party lies in the suburbs. He replied:

It certainly seems that way. Biden was more successful than Clinton in stanching the Democrats’ bleeding in rural, white areas, especially in Pennsylvania where it mattered a lot. As an older, straight, white, male working-class guy, he might have been the only Democrat who could have pulled that off. Whoever the Democrats next candidate for president is, that person is unlikely to share many characteristics with Biden. So more highly educated people in the suburbs are going to be critical to future Democratic success.

Jennifer Victor, a political scientist at George Mason University, argued in an email that “the organizing principle around the parties is increasingly defined by social identities, rather than ideology, policy preferences, or organized interests.” Republicanism, she continued,

has come to be defined by Donald Trump and his brand of “Trumpism,” which is characterized as an America-first, masculine-bravado, defense of traditional social hierarchies. Democratic Party affiliates, on the other hand, are increasingly organized around the counternarrative to Trumpism. In this way party politics is strongly driven by negative partisanship.

In 2020, the presidential wing of the Democratic Party was sustained by what Victor calls “the counternarrative to Trumpism.” That counter- narrative was less than adequate for the congressional and state legislative wings of the party. In 2022, Trump will be neither on the ballot nor in the White House. In 2024, Democrats might luck out with Republicans nominating Trump, or even his son Don Jr., although neither outcome appears likely right now.

Instead, the Democratic Party faces the daunting task of uniting a party with competing moderate and left factions built on a fragile “upstairs-downstairs coalition” — a party that stretches ideologically from Joe Manchin to Alexandria Ocasio-Cortez and financially from the 18th Congressional District in California’s Silicon Valley with a median household income of $149,375 to Michigan’s 13th District in Detroit with a median household income of $39,005.

Democrats struggled through similarly adverse circumstances during the administrations of Bill Clinton and Barack Obama, but the outcome of the subsequent elections in 2000 and 2016 suggest a tough road ahead for Biden and his party, although both came close to putting their chosen successor in office. The suddenly key suburban moderates had little tolerance for the antics of the Trump administration; they are likely to have little tolerance for a faltering — let alone failing — Democratic administration.

This places a particularly heavy burden on Biden, both as the leader of a divided country and as the head of a fragile, if not fragmented, Democratic coalition. He will shortly have the opportunity to demonstrate whether or not he is equipped to meet the challenge.

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