Joe Biden swept to victory in Florida, Illinois and Arizona on Tuesday, building on a remarkable surge as he powers toward the Democratic presidential nomination.
The former vice president’s third big night in as many weeks came amid tremendous uncertainty as the Democratic contest collides with efforts to slow the spread of the coronavirus.
Polls were shut in Ohio, and although balloting went ahead as scheduled in the three other states, election workers and voters reported problems.
The former vice president’s victories were another blow to Vermont senator Bernie Sanders, whose early strength has evaporated as African Americans and working-class white people across the country side with Mr Biden.
Meanwhile, President Donald Trump clinched the Republican Party nomination, surpassing the necessary delegate threshold.
Mr Trump, who had only token opposition, now has more than the 1,276 delegates needed after winning Tuesday’s Florida and Illinois primaries, according to The Associated Press’ delegate count.
This is the earliest the delegate calendar permits a Republican to clinch the nomination.
This week’s Democratic primaries marked the third week in a row Mr Biden began piling up wins after his victory in South Carolina last month revived his once-flagging campaign.
Since then, most of his party’s establishment lined up behind him as the best option to unseat President Donald Trump in November.
As many people work from home and as schools and businesses close, the primary has remained in limbo, devoid of in-person rallies.
Mr Sanders’ pathway to the nomination has dramatically narrowed, but he isn’t expected to leave the race — betting that the national political landscape will look different as the virus continues to reshape life.
Mr Sanders has staged virtual rallies that his campaign says have been watched by millions, and he used the coronavirus outbreak to promote the need for universal, government-funded health care under his signature issue, “Medicare for All”.
Mr Biden’s campaign is also taking nothing for granted, although the former vice president has declared he would select a woman as his running mate — suggesting such preparations for his clinching the nomination may be underway.
Officials in Ohio took the unprecedented step of closing polls Monday, mere hours before they were set to open, pushing back the state’s primary until June.
Turnout was expected to be affected in Illinois, Florida and Arizona, which went ahead with voting even as federal authorities urged people to stay home whenever possible and not to gather in groups of larger than 10.
Democratic National Committee Chairman Tom Perez blasted Ohio for breeding “more chaos and confusion”.
He sought to head off more states taking similar actions, urging those with forthcoming primaries to expand vote-by-mail and absentee balloting, as well as polling station hours, so that efforts to stop the spread of the coronavirus don’t further derail his party’s nomination contest.
As we continue to fight for universal health care and paid leave, it has never been more important to strengthen the trade union movement. Workers must have the right to collectively bargain for better pay, stronger benefits, and more power over their lives.— Bernie Sanders (@BernieSanders) March 17, 2020
“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,” Mr Perez said in a statement.
Four other states — Louisiana, Georgia, Kentucky and Maryland — have already moved to push back their primaries, and others could follow suit.
That has left the Democratic primary calendar empty until March 29, when Puerto Rico is scheduled to go to the polls — but island leaders are working to reschedule balloting there, too.
Voting on Tuesday saw problems pop up across the country, with many poll workers dropping out in light of the coronavirus.
The virus has cast a shadow over the entire Democratic primary race, with debates over policy minutiae taking a back seat to issues of life and death.
Meanwhile, politicians on both sides expressed frustration Tuesday after Ohio’s primary was postponed until June by the state’s elected officials.
The Ohio Democratic Party lodged a lawsuit on Tuesday afternoon over Secretary of State Frank LaRose’s decision to set a new date, saying that power rests only with the state’s Legislature.