Joseph R. Biden Jr. easily defeated Senator Bernie Sanders in the Florida and Illinois primaries on Tuesday, all but extinguishing Mr. Sanders’s chances for a comeback on an Election Day conducted amid a series of cascading disruptions from the coronavirus pandemic.
Mr. Biden, the former vice president, was seen as having a strong advantage over Mr. Sanders in a third state, Arizona, but early in the evening he had not yet been declared the winner there. Should Mr. Biden sweep the night, he could amass the kind of insurmountable delegate lead that could greatly intensify pressure on Mr. Sanders to end his campaign.
The routs in Florida and Illinois represented both a vote of confidence in Mr. Biden from most Democrats, and a blunt rejection of Mr. Sanders’s candidacy by the kind of large, diverse states he would have needed to capture to broaden his appeal beyond the ideological left.
Mr. Sanders, of Vermont, has struggled since his first presidential campaign in 2016 to win over black voters in larger numbers and to persuade voters who do not share his ethos of democratic socialism that he can be trusted to lead the party into the general election.
In the two biggest states voting on Tuesday, Mr. Sanders failed: Mr. Biden carried Illinois by a wide margin, keeping intact his winning streak in the large Midwestern primary states, after previously winning in Minnesota and Michigan. And the victory in Florida was a particularly sharp repudiation of Mr. Sanders: Many moderate and conservative Hispanic voters in the state had recoiled from his past praise of leftist governments in Latin America, including his admiring remarks about certain achievements of Fidel Castro’s Cuba.
But the day of voting may have been most notable for a state that did not vote. The turmoil caused by the coronavirus upended plans for a primary election in Ohio, where state officials postponed voting in an abrupt maneuver that barely survived last-minute legal scrutiny. Four other states have also taken steps to delay their primary elections until late this spring, with Maryland on Tuesday becoming the latest to push back voting.
In the states that did vote, there were signs that the virus had dampened voter turnout, and that the Democratic presidential campaigns and other party leaders were not engaged on Tuesday in the traditional all-out push to drive supporters to the polls.
It made for an extraordinary day in the country’s electoral history, featuring candidates who could not campaign in public and party officials who were navigating the delicate line between protecting public safety and the civic right to nominate a candidate for the nation’s highest office.
In a gesture to the gravity of the moment, Mr. Biden used much of his brief victory address — via a balky live stream from his Wilmington, Del., home — to discuss the virus and to reassure the country.
“We’ll get through this together,” said Mr. Biden, trying to project a presidential bearing to a rattled nation. He only fleetingly mentioned Tuesday’s results, noting he had “a very good night,” before directly speaking to Mr. Sanders’s youthful supporters, a voting group he is trying to court.
“I hear you, I know what’s at stake, I know what we have to do,” Mr. Biden said. “Our goal as a campaign, and my goal as a candidate, is to unify this party and unify this nation.”
Praising the “remarkable passion and tenacity” of Mr. Sanders and his supporters, the former vice president said he and the senator disagree on tactics but “share a common vision.”
Mr. Sanders did not deliver a speech about the primary results, but earlier in the evening he broadcast his own online address calling for sweeping government action to remedy the economic damage of the crippling virus, including an initiative to give people $2,000 monthly payments for the duration of the crisis.
“We must make certain that this health and economic crisis is not another moneymaking opportunity for corporate America and for Wall Street,” Mr. Sanders said, eschewing any mention of the primaries.
Mr. Biden’s victory in Florida relied in part on a familiar coalition of voters who have supported him in other states, including African-Americans, political moderates and voters over 50, according to a pre-election poll there. But polls suggested that Mr. Biden would also finish narrowly ahead of Mr. Sanders with people who described themselves as very liberal, and that the former vice president would beat him by double digits among voters who said the economic system needed a complete overhaul.
The virus drove down turnout in some Florida localities, but even with the pandemic turnout was still higher than in 2016 in a handful of suburban and affluent communities, such as Naples and suburban Jacksonville. Mr. Biden won both jurisdictions handily, as he has in other upscale precincts since Super Tuesday, a sign of his strength with the sort of voters who could swing the general election.
The results appeared somewhat more competitive in Illinois, which has a younger and more liberal electorate than Florida’s. In Illinois, Mr. Sanders was dominating with voters under 45 and among the most liberal Democrats to cast ballots.
In all three states, voters said by huge margins that they believed Mr. Biden was the candidate best prepared to handle a major crisis.
More than a million people cast ballots early or by mail in advance of Tuesday’s primaries, according to election officials in the three states, suggesting that the contests could represent a clear enough statement on the trajectory of the Democratic campaign.
Mr. Biden had built a formidable lead over Mr. Sanders since the start of the month, leaping far ahead of him in national polls and collecting 151 more delegates out of the 1,805 allotted so far, according to a New York Times analysis. Influential leaders at every level of Democratic politics have swung behind Mr. Biden, reinforcing his position as the overwhelming choice of the party’s moderate establishment.
In just the states voting on Tuesday, Mr. Biden had the support of Illinois’s powerful governor, J.B. Pritzker, both its senators and the mayor of Chicago; Arizona’s Democratic senator, Kyrsten Sinema; and every Democratic member of Florida’s congressional delegation. Over the weekend, the former vice president was backed by the National Education Association, the teachers’ union that is the largest organized labor organization in the country.
Mr. Sanders has not indicated that he is likely to stand down as his losses mount, and his advisers indicated in the run-up to Tuesday’s primaries that he was likely to stay in the race and continue collecting as many delegates as he can. He used a debate on Sunday to deliver his most focused critique so far of Mr. Biden’s policy record and personal judgment, on a range of defining issues for Democratic voters.
But both candidates are still adapting to the halting new pace of the campaign, which is now strictly confined by several factors: a patchwork of travel restrictions and local shutdowns; a near-blackout of news unrelated to the pandemic; and the two aging candidates’ concern for their own health.
For Mr. Sanders, 78, the country’s sudden turn away from the campaign may have the effect of smothering even the most determined effort to block Mr. Biden, 77, or broaden his own political appeal.
The Vermont senator has long relied on huge rallies and a loud microphone in the national news media to advance his candidacy, and for the moment both tools appear to be unavailable. And Mr. Sanders may face growing complaints, even from liberal Democrats, that he is keeping the party divided at a moment when the stakes of the election have never been clearer or more urgent.
Yet the campaign freeze may be an obstacle for Mr. Biden, too, particularly if Mr. Sanders persists with a long-shot challenge that could take months to resolve. Mr. Biden had been hoping to extinguish Mr. Sanders’s candidacy with a string of landslide victories, continuing his momentum into the contests this week and then into the Georgia primary this coming Tuesday.
But like Ohio, Georgia recently announced it was moving its primary election; there is now the possibility of a major backlog of primaries in the late spring that could tempt Mr. Sanders to stay in the race and hope for a major shift in its political fundamentals.
Even if Mr. Sanders is largely sidelined by the coronavirus crisis, his continued presence in the race could hinder Mr. Biden’s ability to establish himself as the presumptive Democratic nominee and to turn his attention exclusively toward President Trump.
While he has been off the trail over the past week, Mr. Biden has begun to run something like a Rose Garden campaign, or whatever the equivalent is for someone who is not already the president: He appointed a public health task force and unveiled a detailed policy agenda for addressing the coronavirus in a formal speech on Thursday. Over the weekend Mr. Biden held a phone call with Senator Elizabeth Warren of Massachusetts, his progressive former rival, and endorsed liberal policies on higher education and bankruptcy reform in an effort to woo the left.
It is not clear how long Mr. Biden and Mr. Sanders might be kept from campaigning altogether. Both men are confronting the likelihood that they will not be able to hold traditional campaign events until well into the spring, at the earliest, and even the possibility that the summer nominating conventions could be endangered by the imperatives of fighting the coronavirus.
The elections on Tuesday offered new evidence of just how difficult it had become to hold any semblance of normal primary elections. There were reports in multiple states of election workers not showing up at the polls; even in densely populated and heavily Democratic areas, like Miami-Dade County in Florida and Cook County in Illinois, voter turnout appeared low on Tuesday morning.
Most of all, the frenzy of sudden, and sometimes contradictory, last-minute announcements in Ohio underscored the potential for outright chaos at the polls. Gov. Mike DeWine, a Republican, declared late on Monday that he would not allow Ohio’s primary to go forward.
After an initial setback in court, Mr. DeWine’s state health director issued an order closing the polls as a health emergency, and early on Tuesday morning a state court allowed that decision to go forward. It was not immediately clear how Ohio would go about reviving the primary, but Mr. DeWine said on Tuesday that it would have been irresponsible to proceed with in-person voting this week.
“This is a gathering of people, and what we’ve tried to do is explain to Ohioans we cannot have large gatherings,” Mr. DeWine said of the primary election, in a television appearance on Tuesday.
Election officials in the other three states voting on Tuesday conceded that the coronavirus was a cause for concern but said that they were taking steps to sanitize the polls. And in perhaps a bleak reflection of the country’s present condition, Katie Hobbs, Arizona’s secretary of state, warned that there was “no guarantee that there will be a safer time to hold this election in the near future.”
“The longer we wait, the more difficult and dangerous it could become,” she said.