Former United States President Donald Trump is one step closer to an election rematch against Democrat Joe Biden, as he secured a decisive victory in New Hampshire’s first-in-the-nation primary on Tuesday.

Within minutes of the state’s polling stations closing, US media announced Trump would beat his Republican rival Nikki Haley by a substantial margin, dealing a powerful blow to her campaign.

The final results have not yet been announced, but projections showed Trump with a double-digit lead with about half of the votes counted.

The ex-president’s resounding victory follows a similarly strong showing in the Iowa caucuses last week, cementing his lead in the race for the Republican presidential nomination ahead of November’s general election.

No presidential candidate has ever won the first two contests on the presidential race calendar — as Trump has now done — and not emerged as their party’s nominee.

New Hampshire had been framed as Haley’s last best chance to make a dent in Trump’s runaway lead. But despite her loss, the former United Nations envoy said in a speech on Tuesday night that she plans to continue her campaign.

“This race is far from over. There are dozens of states left to go,” she told a crowd of supporters after the New Hampshire race was called for Trump. “Today we got close to half of the vote. We still have a ways to go, but we keep moving up.”

Though she readily acknowledged her defeat in the New Hampshire primary, she also took aim at Trump’s fitness for office and his chances against Biden.

“With Donald Trump, Republicans have lost almost every competitive election,” she said. “The worst-kept secret in politics is how badly the Democrats want to run against Donald Trump.”

Trump responded with a fiery speech of his own later in the evening, at his campaign headquarters in Nashua, New Hampshire.

The former president accused Haley of claiming victory even in defeat. “Who the hell was the impostor who went up on the stage before and claimed a victory?” Trump asked.

While most of the attention was focused on Tuesday’s Republican primary results, President Biden also secured a resounding victory in his party’s primary race despite not appearing on the ballot.

Biden did not participate in the New Hampshire contest due to a scheduling spat between state Democrats and the Democratic National Committee, but his supporters launched a successful campaign to urge voters to write the president’s name on the ballot anyway.

He easily bested two distant Democratic challengers, Minnesota Representative Dean Phillips and author Marianne Williamson, who were on the ballot along with a host of little-known candidates.

“Despite President Biden’s absence from the ballot, Granite Staters still turned out in robust numbers to show their support for the great work that the Biden-Harris Administration has done to grow the economy, protect reproductive freedoms, and defend our democracy,” the state’s Democratic Party chair, Raymond Buckley, said in a statement.

Biden’s victory also came despite reports of a “deepfake” robocall targeted at New Hampshire’s Democratic residents: Using an imitation of Biden’s voice, the call discouraged voters from participating in Tuesday’s primary.

In a statement after the results were announced, Biden’s re-election campaign manager Julie Chavez Rodriguez indicated her attention was now focused on Trump, dismissing Haley’s prospects as a Republican contender in the general election.

“Tonight’s results confirm Donald Trump has all but locked up the GOP nomination, and the election denying, anti-freedom MAGA movement has completed its takeover of the Republican Party,” Chavez Rodriguez said.

“Donald Trump is headed straight into a general election matchup where he’ll face the only person to have ever beaten him at the ballot box: Joe Biden,” she added.

Andrew Smith, a political science professor and president of the University of New Hampshire’s Survey Center, said the margin of victory in both the Republican and Democratic primaries was more or less what was expected heading into Tuesday.

“Haley will likely have to drop out after this. She may stick around until South Carolina, but she is just playing out the string,” Smith told Al Jazeera in an email.

New Hampshire has held the first primary in the US since 1920. Experts predicted the state would be markedly more receptive to Haley than other states she will later face. Her next must-win stop will be her home state of South Carolina.

Christopher Galdieri, a professor at New Hampshire’s Saint Anselm College, said Haley made a “smart move” by using her speech “not so much as a concession but as an opportunity to introduce herself to voters across the country”.

But Galdieri said it was unclear if that would be enough to keep her campaign going amid Trump’s iron-clad grip on the Republican Party.

“Republicans are so wedded to Donald Trump — they have so wrapped up being a good Republican with being a good Trump supporter — that it’s just really hard for them to shake out of that,” he said.