Joe Biden swept another round of delegate-rich contests Tuesday – winning in Florida, Illinois and Arizona – further cementing the former vice president as the dominant front-runner in the race for the Democratic presidential nomination over Bernie Sanders as the coronavirus threat scrambles the primary calendar for the foreseeable future.

Florida and Illinois will award a hefty 219 and 155 pledged delegates, respectively, while Arizona is worth 67 delegates. Together, the contests are likely to only add to the pressure on Sanders to reconsider his presence in the race.

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Last week, Sanders vowed to press on after a string of defeats, signaling he wants to continue to pressure Biden to embrace more progressive policies.

"Our campaign has had a very good night," Biden told supporters in Wilmington, Delaware, before the Arizona race was called. "We've moved closer to securing the Democratic Party's nomination for president. And we're doing it by building a broad coalition that we need to win in November, with strong support from the African-American community, the Latino community, high school-aged people, educated people ... labor, teachers, suburban women, veterans, firefighters and so many more."

Once again, he extended an olive branch to Sanders in a nudge to convince him to step aside, though as recently as their debate on Sunday, Sanders showed little inclination to accept.

"Senator Sanders and I may disagree on tactics, but we share a common vision for the need to provide affordable health care for all Americans, reducing income inequality that has risen so drastically, to tackling the existential threat of our time, climate change," he said. "Senator Sanders and his supporters have brought a remarkable passion and tenacity to all of these issues. ... Together, they have shifted the fundamental conversation in this country. So let me say, especially to the young voters who have been inspired by Senator Sanders. I hear you."

SANDERS REVEALS HOW HE'LL PAY FOR PROGRAMS -- ARE THERE ISSUES?

Earlier in the evening, Sanders gave an online address as well focused on the pandemic, providing a detailed list of proposals to address the medical and economic issues caused by the novel coronavirus.

Sanders said his proposals would cost "at least $2 trillion" and would include monthly $2,000 checks to American households.

In Florida, a key swing state in the general election, Sanders was walloped.

Biden was ahead in the state by a massive margin of 61.5 percent to 22.7 percent, with 82 percent of precincts reporting. The rout was somewhat expected, with the state's sizable Cuban- and Venezuelan-American population largely resistant to Sanders' democratic socialist politics and many voters angered after he defended former Cuban dictator Fidel Castro's literacy programs.

Twenty percent of Democratic primary voters in the Florida primary were Hispanic -– a group that typically has been a strength for Sanders. Six-in-ten voted for Biden, who received approximately two-thirds of the vote among Puerto Ricans and almost six-in-ten among Cubans, according to the Fox News Voter Analysis.

FOX NEWS VOTER ANALYSIS: FULL METHODOLOGY

Despite ongoing concerns about the coronavirus, seniors made up more than one-third of the electorate in Florida – the highest portion in any primary surveyed this year, the Fox News Voter Analysis showed. Biden easily won voters over the age of 65, with almost eight-in-ten supporting him.

Electability continued to play a factor in Biden's favor.

Across all states voting on Tuesday, voters said they believed Biden was better positioned to win in November.

Meanwhile, Trump easily clinched the Republican presidential nomination with wins in the Illinois and Florida Republican primaries, officially dashing the hopes of any of the extreme long-shot candidates who challenged him in that primary.

A total of 441 delegates was at stake in the Democratic primary on Tuesday, and the big question was whether the coronavirus would affect turnout at the polls. Some early indications were that turnout in Florida actually may have been higher than 2016 figures.

DNC CHAIR URGES VOTERS TO CAST BALLOTS BY MAIL

Biden is moving closer to securing the Democratic presidential nomination but had faced the possibility of a setback if the older voters who tend to support him didn't show up. Sanders, meanwhile, couldn't afford to lose support from young voters who have been his most loyal supporters. In the end, Biden did not appear to suffer any measurable loss of support.

Problems related to the virus scare still reportedly popped up across the country, including in Florida, the biggest delegate prize of the evening.

In Okaloosa County on the Panhandle, two dozen poll workers dropped out, leaving supervisors scrambling to find replacements.

Millions of voters have already participated in some form of early voting. But there were some signs on Tuesday that voters — and poll workers — were staying home.

PROGRESSIVES SLAM PEREZ AS 'IRRESPONSIBLE' FOR ALLOWING PRIMARIES AMID OUTBREAK

In Burbank, a small community southwest of Chicago, most of the voting stations stood empty at 8 a.m., the Associated Press reported. Only 17 people had voted, a pace that officials said was unusually slow.

In Palm Beach County, Florida, 800 volunteer poll workers backed out on Monday and just 100 new volunteers offered to take their place.

In Illinois, there was a push to relocate about 50 Chicago-area polling places after locations canceled at the last minute and said they would not be available for use on Tuesday.

This may be the last batch of primaries for weeks -- at least of primaries featuring in-person voting -- should states holding upcoming contests continue to push them off.

Leaders in Ohio called off their primary just hours before polls were set to open as the federal government urged Americans not to gather in groups of 10 or more and asked older people to stay home. The state's Democratic Party said it was weighing options for challenging that move, which was pushed by the Republican governor.

Georgia has delayed its primary from March 24 to May 19, and Louisiana from April 4 to June 20. Additionally, Maryland has moved its April 28 primary to June 2, and Kentucky has pushed its primary from May 19 to June 23.

The Democratic National Committee (DNC) has reportedly warned that states that delay their primaries past June 9 could face a hefty delegate penalty -- angering some commentators who call the ultimatum reckless given the threat posed by coronavirus.

“The right to vote is the foundation of our democracy, and we must do everything we can to protect and expand that right instead of bringing our democratic process to a halt,” DNC chairman Tom Perez said in a statement. He is urging states to expand options like voting by mail in upcoming contests.

The tumult surrounding the virus has left the primary campaign in a state of suspended animation, but Sanders currently faces an increasingly tough path to the nomination. The coronavirus outbreak and its impact on the primary calendar could only amplify calls for Sanders to drop out of the race.

About half of the delegates in the Democratic primary have already been awarded and, with Biden looking at another big night Tuesday, he will pad an already large and perhaps insurmountable lead.

CORONAVIRUS THREATENS TO UPEND REMAINING PRIMARIES, CONVENTIONS

Biden's quest for his party's nomination now seems within reach. He needs less than half of the remaining delegates to become the nominee.

Fox News' Victoria Balara, Kimberly Anderson, Paul Steinhauser, and The Associated Press contributed to this report.