Joe Biden won the endorsement of America's biggest car workers union Wednesday, as the race for the White House dramatically revved up following Donald Trump's victory in the New Hampshire primary.
The Democratic president and his Republican predecessor both sought to portray a rematch in November's election as inevitable, even if polls show a sequel of the traumatic 2020 contest is something most Americans don't want.
After Trump left his only remaining challenger Nikki Haley in the dust in New Hampshire on Tuesday to cement his grip on the Republican nomination, it was Biden's turn for good news in his bid for a second term.
Wearing a black union baseball cap, Biden, 81, stood with his arm aloft after the influential United Auto Workers union backed him in a major boost for his battle with Trump for the blue-collar vote.
"Let me just say I'm honored that you have my back and I have yours," Biden said in Washington as union members chanted his name.
Earlier, they had booed each mention of 77-year-old Trump as powerful UAW chief Shawn Fain said that the tycoon and twice-indicted former president "doesn't care" about workers.
Fain said Trump wanted to "screw the American working class".
The endorsement came as the Biden campaign pivoted even more sharply towards an election battle with Trump, in the wake of the Republican's second primary victory in a row.
Haley, Trump's former UN ambassador, vowed Wednesday to fight on, but no Republican has ever won both opening contests and not ultimately secured the party's nomination.
Trump previewed the divisive campaign rhetoric to come with a victory speech that attacked Haley for having a "very bad night" and even lashed out at her dress.
"I don't get too angry, I get even," Trump said.
Haley had hoped for a major upset in New Hampshire, but Trump won by around 54 percent to 43 percent.
She went back on the offensive Wednesday, heading to South Carolina, where she launched attack ads targeting Trump as "too much chaos" as she tries to turn around weak polling in her home state ahead of its February 24 primary.
"Trump is completely consumed by his own perpetual drama and grievances," Haley's communications director Nachama Soloveichik said.
Biden meanwhile said it was "clear" he would be facing Trump in November, apparently relishing the chance of a rematch with the man he beat four years ago despite lackluster poll ratings.
US media said that the New Hampshire results held hope for Biden, with the divisive Trump failing to win over independents and moderate Republicans.
Biden's campaign sees the UAW endorsement, and its campaigning muscle, as crucial to woo the working class voters who propelled him to power in battleground states in 2020 -- the cohort that swung to Trump in 2016.
The UAW this time held out for months on endorsing Biden amid disagreements over his push for electric vehicles. In the 2020 election it endorsed him despite a significant chunk of members being pro-Trump.
Biden has as a result relentlessly courted the union and became the first US president in history to appear on a picket line last year during its strike against the big three US car giants.
The union has also been at odds with Biden's support for Israel's offensive on Gaza after the October 7 Hamas attacks, officially calling in December for a ceasefire.
Biden's speech to the UAW was briefly disrupted by pro-Gaza protesters before they were dragged away.
"We're going to continue to push for a ceasefire," Fain told reporters after his speech. "We're going to continue to push the White House and hope that they join us."
