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WASHINGTON — Joe Biden doubled his delegate lead over Bernie Sanders in Tuesday's primaries, giving him a nearly insurmountable advantage after sweeping Florida, Illinois and Arizona, according to NBC News projections.

The former vice president now has 315 more delegates than the senator from Vermont — 1,132 to Sanders' 817 — after having started the night with an edge of 154.

Biden has passed the halfway mark and is well on his way to the 1,991 delegates he needs to win a majority of all delegates and capture the Democratic presidential nomination.

Sanders did not address the results Tuesday night. He spoke earlier on a livestream on his campaign website and focused on the coronavirus pandemic, which has overshadowed the latest round of primary contests.

Biden, speaking via livestream from his home, made a clear appeal to Sanders' supporters.

"Senator Sanders and his supporters have brought a remarkable passion and tenacity to all of these issues. And together they have shifted the fundamental conversation in this country," Biden said.

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Biden then spoke directly to the young voters "inspired" by Sanders.

"I hear you, I know what's at stake, I know what we have to do. Our goal as a campaign and my goal as a candidate for president is to unify this party and then to unify the nation," said Biden, who exit polls have shown has been running poorly among younger voters.

Meanwhile, President Donald Trump on Tuesday night secured the number of delegates he needs to become the Republican Party's presumptive nominee once again, NBC News projects.

Ohio postponed its primary, which had also been scheduled for Tuesday, until June because of the coronavirus outbreak.

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Biden entered the night with an already commanding lead after overwhelming Sanders on Super Tuesday and in more recent contests, including a late-breaking victory in Washington that NBC News projected on Monday.

Florida, which has the fourth-largest number of delegates at stake of the entire year, significantly stretched Biden's lead after he won every county in the state. In 2016, Sanders got blown out in Florida, but he was at least able to win nine counties and a third of the delegates.

While results were still coming in, Biden is on track for a similarly strong win in Illinois, where Sanders is currently winning just one county — home to the University of Illinois — and although Arizona is closer, Biden will still extract more delegates from the state.

The former vice president's growing delegate lead makes a comeback by Sanders increasingly unlikely as the number of delegate-rich states on the calendar dwindles from this point on.

Because Democrats award delegates in proportion to each candidate's vote share, Sanders would likely need to win coming states by very lopsided margins to catch up to Biden.

Meanwhile, six future contests have so far been delayed by the coronavirus outbreak, including the next two that had been set for this month, Georgia and Puerto Rico.

The means that after a jampacked Democratic presidential calendar with election nights every week for almost two months, there is no vote on the books in any states until April 4, when Hawaii, Alaska and Wyoming will weigh in.

Those states are expected to be friendlier territory for Sanders but don't offer many delegates. The next big contest is scheduled to be held in Wisconsin on April 7.