Joe Biden scored decisive victories in all three major Democratic primaries Tuesday, earning him a nearly insurmountable lead over rival Bernie Sanders in their race for the party's presidential nomination.

Democratic presidential hopefuls former US vice president Joe Biden (left) and Senator Bernie Sanders engage each other in the 11th Democratic Party 2020 presidential debate. Photo: AFP

As the United States grappled with combating the spreading coronavirus pandemic, voters handed the former vice president victory in delegate-rich Florida, as well as Illinois and Arizona.

The command performance speaks to the eagerness of many Democrats to coalesce around a moderate flag bearer, to challenge Republican President Donald Trump, after several other candidates dropped out of the contest in recent weeks and endorsed Biden.

In Florida, the 77-year-old won 62 percent to 23 percent against Sanders, a 78-year-old self-described "democratic socialist" senator from Vermont.

Biden was ahead by 23 percentage points in Illinois, with 89 percent of precincts reporting.

And in Arizona, where polls closed last, Biden was coasting to a third definitive win - and his 19th victory in the last 24 contests.

"Our campaign has had a very good night," Biden said in televised remarks from his home in Delaware.

"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."

By all accounts it is an astonishing reversal of fortune for Biden, whose campaign was left for dead just one month ago after poor showings in early voting states.

But following a string of victories in high-profile contests starting with South Carolina in late February, and continuing into his show of strength Tuesday, Biden now has a commanding lead in the all-important race for the delegates needed to become the nominee.

Political analyst David Axelrod concluded that Sanders was a mortally wounded candidate.

"No Dem has ever come back from anything like this deficit," tweeted Axelrod, chief strategist for Barack Obama's two successful presidential campaigns.

"The race for the nomination is over. That is the reality @BernieSanders faces."

On Tuesday Biden's delegate count stood at 1,147 compared to Sanders's 861, according to a New York Times rolling tally. A candidate needs 1,991 delegates to secure the Democratic nomination and face Trump in the November election.

Biden has long said that Americans want pragmatic results, not the political "revolution" advocated by Sanders.

But he reached out on Tuesday by appealing to Sanders supporters.

"To young voters who have been inspired by Senator Sanders, I hear you," Biden said.

Biden said he and Sanders "share a common vision" to expand health insurance, address economic inequality and fight climate change.

Sanders delivered a 20-minute speech online Tuesday. 


Newspaper headline: Biden’s clean sweep all but seals his nomination