After Democrats' strong victories in November's elections, The Fix's Aaron Blake breaks down what the momentum brings for Democrats, Republicans and President Trump. (Jenny Starrs/The Washington Post)

After an election night that surpassed their wildest hopes, Democrats returned to a familiar squabble: How should they run to win in 2018?

Ralph Northam’s victory in the Virginia governor’s race, part of a blue wave that spread across the country, gave Democrats confidence they had not known since the hours before Hillary Clinton lost the presidency. Some Democrats even saw an end — or at least a pause — to infighting between a much-derided “establishment” and their left-wing base.

“Jobs, health care and education for all — we run on the basics,” said Sen. Tim Kaine (D-Va.), who stumped across his state for Northam and successful House of Delegates candidates. “We avoid stupid infighting.”

It’s not quite that peaceful. In interviews, memos and a flurry of conference calls, left-wing groups created or rebuilt since the 2016 election claimed the electoral wins as a victory for their philosophies and gave little ground in the battle over what direction the party should take or which issues win.

But a larger conclusion also emerged for many Democrats — that the litmus tests of a restive base can linger without unraveling campaigns or keeping voters at home. Tom Steyer, a billionaire whose environmental group, NextGen America, poured money into Virginia, said the race was too important to stay out of despite disagreements about pipelines. Many more voters than expected agreed this week — a model for more victories next year, even for candidates who don’t fit every Democrat’s vision of perfection.

Danica Roem, a Democrat who won a House of Delegates seat in Virginia on Tuesday, falls to her knees after getting a congratulatory call from former vice president Joe Biden. (Jahi Chikwendiu/The Washington Post)

“I think the reason people are voting for them is that they want to say, ‘We’re going to elect everybody that we think would upset Donald Trump,’ ” said Rep. Luis V. Gutiérrez (D-Ill.). “ ‘We think Donald Trump would be upset to see Latinos and women and gays and different people from different religions. Anything that isn’t white, Anglo-Saxon Protestant? We’ll vote for that.’­”

For NARAL, an abortion rights group, Northam proved “that pro-choice candidates can run and win on their support for reproductive freedom.” Run for Something, founded by Clinton’s 2016 email director, helped first-time down-ballot candidates across the country outperform the top of the ticket. Democratic Socialists of America celebrated the victory of Lee Carter, a Marine veteran who won a Virginia House of Delegates seat in a race the state party considered unwinnable.

“We saw a lot of reverse coattails in Virginia, driven by inspiring candidates,” said Adam Green, co-founder of the Progressive Change Campaign Committee. At least 13 of the 15 delegate candidates backed by the PCCC were victorious.

Most Democrats dodged the argument altogether. Tuesday’s victories were broad, pulling Democrats into power in once-conservative suburbs and helping far-left candidates in cities win landslides.

Rep. Cheri Bustos (D-Ill.), a moderate from southern Illinois who is helping Democrats craft an economic-focused campaign message next year, said she was especially heartened by Virginia Democrat Danica Roem, who became the first openly transgender person to win a seat in the House of Delegates, defeating one of the state’s most conservative, divisive lawmakers.

“Look what she was talking about,” Bustos said. “She wasn’t talking about the fact that she was transgender — other people were talking about that. She was talking about transportation. No matter who our candidates are or what their candidates are, the number-one lesson is, focus on the economy.”

Vi Lyles, the next mayor of Charlotte, celebrates her victory with her granddaughters Tuesday. (Jeff Siner/Charlotte Observer/AP)

Senate Minority Leader Charles E. Schumer (D-N.Y.) said that national political dynamics were beginning to look like they did in late 2005, a year before Democrats retook control of Congress. President Trump’s unpopularity seemed to have stoked what Schumer expected last year — a suburban rejection of Republicans who are stumbling over how to handle their president.

“We are getting our best candidates to run. We are unified like the party was in Virginia. We are winning in places we didn’t think possible, and the other side is busy fighting with each other,” Schumer told reporters Wednesday. “Our Republican colleagues in the House and the Senate, while they grumble about him to us privately, are afraid to change course.”

Until Tuesday night, it had been the Democrats, roiled by fresh arguments about the 2016 presidential primary, who were grumbling privately. Their victories, like Trump’s, suggested that party infighting was not necessarily important to voters seeking change.

Rep. Brendan Boyle (D-Pa.) said that his suburban Philadelphia district saw “more first-time candidates who’d never thought about running this cycle than all the other cycles I’ve been in politics” — and that most of them won.

Over the summer, Boyle delivered a keynote speech at a fundraiser for Democrats in Delaware County, Pa., a county outside his congressional district that had been dominated by Republicans for more than a century. At the fundraiser he met Brian Zidek, a man who “woke up the morning after the election in 2016” and decided to run for a County Council seat. On Tuesday, Zidek was one of two Democrats elected to the five-member council, breaking a century-long Republican grip.

“Until Tuesday night, that was one of the question marks I had in my mind: To what extent would voters treat their local Republicans the same way they view Trump?” Boyle said. “It was clear Tuesday night they made no distinction.”

Rep. Gerald E. Connolly (D-Va.), who watched his Fairfax County turn deep blue on Tuesday, called the president “the gift that keeps on giving” for local Democratic candidates.

“I don’t think there’s any simple formula, and I don’t think it mattered,” he said. “What mattered is that they were Democrats.”

Other Democrats argued that the party had won by sharpening voters’ focus on why government had stopped working for them. Former attorney general Eric H. Holder Jr., who leads a well-funded campaign to end legislative gerrymandering by electing Democrats, said he was pleased to see that Northam campaigned on a pledge not to approve new legislative and congressional maps unless they are drawn up by an independent commission.

“I think that ultimately resonated with people looking for fair line-drawing after the census in 2020,” Holder said. “That’s something, and particularly out of Virginia, about which I’m very optimistic.”

Democratic centrists, meanwhile, argued that the Virginia race proved that the party needed to tack away from the left. In a tweet, former Tennessee congressman Harold Ford Jr., who once led the moderate Democratic Leadership Council, said that Northam’s victory was a win for “Blue Dog” moderates, a dwindling element in the party.

Matt Bennett, a spokesman for the center-left Third Way, also emphasized that Northam had won after defeating progressive primary challenger Tom Perriello, a former congressman who had been endorsed by Sen. Bernie Sanders (I-Vt.).

“Democrats in Virginia took a look at both approaches, and they rejected rigid ideology and litmus test politics and chose a broad, inclusive path,” Bennett said in a statement. “The general election voters of Virginia ratified that choice in a resounding fashion.”

Perriello, reached Wednesday evening, was amused by the Third Way’s analysis.

“If we’ve reached the point where Third Way is celebrating a $15 minimum wage, free college and criminal-justice reform, I’ll take it,” Perriello said. “We saw Ed Gillespie spend a couple of months trying to make the classic tax and spending attacks stick, and they didn’t, either with swing voters or base Republicans.”

Northam had faced criticism from the left, something Republicans attempted to exploit. His first debate with Gillespie, the Republican nominee, was interrupted by a protester decrying Northam’s neutral stance on building energy pipelines. His victory speech was delayed by protesters heckling him for opposing “sanctuary cities” in the commonwealth. In the campaign’s waning days, reporters asked why Sanders had not campaigned for Northam, and a left-wing group condemned his sanctuary-city stance as “racist.”

But Northam, running in a state that has trended away from Republicans, made few other concessions to the center. In a memo to reporters after Northam won his primary, Gillespie’s campaign warned that his endorsement of a $15 minimum wage and stiff pollution controls opposed by friends of the coal industry would make him unelectable.

“Ralph Northam is far to the left of the incumbent Democratic governor, previous Democratic governors and gubernatorial nominees, and, most importantly, the Virginia electorate,” wrote Gillespie’s campaign manager, Chris Leavitt.

In an interview Wednesday, Sanders said the reason he did not stump for Northam was that he was not asked to, and he dismissed the idea that the election validated “centrist” politics at the expense of the populist left.

“Northam won because people today, more than perhaps any time in my lifetime, realize that you can’t sit it out,” Sanders said. “Whether Tom Perriello would have done better than Northam — nobody knows that.”