Expected wins at Georgia, Mississippi and Washington give each contender the delegate count needed to claim nomination at party convention.
Primary elections in Georgia, Mississippi and Washington on Tuesday handed Biden the Democratic nomination and Trump the nod from the Republican Party.
Biden, who had no serious competition in his party, reached the required 1,968-delegate threshold to be nominated while Trump, whose last rival Nikki Haley withdrew from the race last week, also passed the mark of 1,215 delegates needed. Both will be officially nominated at their parties’ conventions in August and July, respectively.
The widely expected results set up the first US presidential election rematch in nearly 70 years, as well as a contest between two candidates that opinion polls suggest that many voters do not want.
At 81, Biden is already the oldest president in US history, while the 77-year-old Trump is facing 91 felony counts in four criminal cases, involving his handling of classified documents and his attempt to overturn the 2020 election, among other alleged crimes.
Their rematch will almost certainly deepen the country’s political and cultural divides over the eight-month grind that lies ahead until the November 5 election.
In a statement, Biden celebrated the nomination while casting Trump as a serious threat to democracy, accusing him of “running a campaign of resentment, revenge, and retribution that threatens the very idea of America”.
Trump, in a video posted on social media, celebrated what he called “a great day of victory”.
“But now we have to get back to work because we have the worst president in the history of our country,” Trump said of Biden. “So, we’re not going to take time to celebrate. We’ll celebrate in eight months when the election is over.”
Brendon O’Connor, a professor at the United States Studies Centre at the University of Sydney, said it was “remarkable” that the Republican Party put Trump forward for a third election in a row after losing the last contest to Biden in 2019.
“Usually, that’s a sign that you should look for a new candidate,” O’Connor told Al Jazeera.
“I think that [Trump] brings fear to his colleagues [in the Republican Party], challenging him is very hard because of his bullying, name-calling way. His supporters are incredibly loyal and vicious against those who challenge Trump within the party,” he said.
In terms of Biden, O’Connor noted that the history of US elections shows that that an incumbent president would not be challenged if they decided to run again for the presidency.
“Once you’ve won a presidential election once, you’d want to win it twice and be a two-term president. That’s usually a mark of success. So, Biden, despite being 81 years old, I think would want that place in the history,” he said.
Biden, who would be 86 years old at the end of his next term, is working to assure a sceptical electorate that he’s still physically and mentally able to thrive in the job.
He is also dealing with additional dissension within his party’s progressive base, furious that he has not done more to stop Israel’s war on Gaza.
The last repeat presidential matchup took place in 1956, when Republican President Dwight Eisenhower defeated former Illinois Governor Adlai Stevenson, a Democrat, for the second time.