Biden won. Now comes the unimaginably hard part.

Jonathan Allen

WASHINGTON — The good news for President-elect Joe Biden is that he defeated Donald Trump. The bad news is he has to preside over an angry and polarized nation, a broken Congress and the continuing economic and public health crises posed by the coronavirus.

He has promised to unify the country, a brutal task that will require him to manage the expectations of the left wing of his own party and the anger of defeated Republicans. And to enact his legislative agenda, he will have to satisfy a Senate that may be led by Majority Leader Mitch McConnell, R-Ky., depending on the outcomes of remaining races, as well as a House led by Speaker Nancy Pelosi, D-Calif. The political bases of both sides are suspicious of anything that unites them.

That's why many political insiders say Biden will be successful only if his presidency matches a campaign in which he rejected the most extreme proposals of fellow Democrats and embraced coalition-of-the-willing Republicans.

"It's going to be a difficult environment," said Doug Heye, a former leadership aide on Capitol Hill who wrote in Utah Sen. Mitt Romney for president. "He may be the best-suited person to get anything done."

Few are confident that Biden can fulfill his promise to bridge the nation's various political divides. But his patience and compassion, combined with his history of making deals with McConnell, have created a sense of tentative optimism among those who supported him.

"There's a possibility that Biden gets to be a president who passes durable legislation, and when I say durable, I mean legislation that's passed in a bipartisan way," said Rep. Stephanie Murphy of Florida, a leader of the moderate Democratic Blue Dog Coalition in the House who has been critical of the left's policies and tactics. "My fear is that in pursuit of purity, we will abandon progress."

There's good reason for both her hope and her fear.

For years as vice president, Biden was the Obama administration's point man for making necessary but politically uncomfortable deals with McConnell. In 2011 and again on New Year's Eve in 2012, Biden and McConnell hammered out budget agreements that kept the government running and averted national fiscal disaster.

The deals were so unpopular with progressives — the latter pact indefinitely extended President George W. Bush's tax cuts — that Senate Democratic leader Harry Reid of Nevada, got the White House to agree that Biden would no longer be the administration's emissary on budget talks.

Already, progressive groups are making demands on Biden's agenda.

Some progressive designs, like "packing" the Supreme Court and expanding government-run health care, are proposals that Biden would probably have opposed regardless. If McConnell keeps control of the Senate, he may give Biden an easy scapegoat, allowing him to blame Republicans whenever his liberal flank demands action.

At the same time, more centrist House Democrats are unloading on liberal colleagues after a difficult election night in which the moderates' ranks were thinned.

Rep. Abigail Spanberger, D-Va., who leads by about 5,000 votes in her tightly contested re-election bid, told fellow Democrats on a conference call this week that progressives' embrace of the slogan "defund the police" nearly cost her the seat. She called her party's strategy "a failure" after Democratic congressional leaders' predictions of expanding their House majority and flipping the Senate fell well short on Election Day.

The fracture within the House Democratic caucus speaks to the complexity of Biden's problems.

When Biden was elected vice president, Democrats had control of both the House and the Senate and were coming off an election in which they not only took the White House but also expanded their numbers in Congress. That allowed President Barack Obama to enact an economic stimulus law, an overhaul of financial services industry regulations and the Affordable Care Act.

But Biden may not have one-party control of Washington, and with votes still coming in, it is unclear how large his mandate will be. He was also elected by a patchwork coalition that will have its own priorities. Black lawmakers, political operatives and activists helped build a surge of Black voters. White centrists in both parties helped create a small but significant shift toward Biden in key swing states. And white progressives swung in behind Biden despite having preferred other candidates for their party's nomination.

So every constituency in Biden's coalition has reason to believe that it was decisive in his victory and will surely pressure him to address its needs first and foremost. That will make it difficult for Biden to keep his chorus from descending into cacophony.

He hopes to break Washington's decadeslong partisan fever, which has increasingly driven and reflected the nation's political polarization. But the trees of the nation's capital have little low-hanging legislative fruit for the taking right now.

It's not clear whether the current regime — a divided Congress and Trump — will pass an additional coronavirus relief bill during the lame-duck session before the presidency changes hands. If that doesn't happen, Biden is likely to move swiftly to get an agreement in line with his vow to make fighting the pandemic his No. 1 priority. In addition, Trump's failure to sign legislation funding rebuilding roads and bridges — a priority of both unions and the Chamber of Commerce — leaves room for Biden to back an infrastructure deal to help stimulate the economy.

"I think McConnell and Biden will be able to do a deal on a big infrastructure program," said investor Robert Wolf, a major Democratic donor. "They'll also agree to some iterations for health care with Covid. ... The other things on the Biden agenda will be tougher to negotiate, like tax reform."

Heye said tax increases will be dead on arrival in the Senate if Republicans keep control. An opposition Senate would also change the calculus for the composition of Biden's Cabinet, because his nominees would have to pass muster with McConnell.

Murphy, the House Democrat, said it is incumbent on Biden to put forward such mainstream proposals that McConnell has to choose between cooperating and risking political backlash for his party if he doesn't.

"McConnell has demonstrated that he is the most craven political person in Washington, that his moral compass is pointed toward power," she said. "He only does things where there's benefit to him and his party. And so that will make a difficult negotiating partner, no doubt."

So, congratulations, Mr. President-elect. And good luck with all of that.

CORRECTION (Nov. 9, 2020, 6:57 a.m. ET): An earlier version of this story misstated Doug Heye’s choice for president. Heye wrote in Utah Sen. Mitt Romney for president; he did not support Joe Biden.