Donald Trump pushed closer to victory over Kamala Harris on Wednesday, leaving the Democrat the narrowest of remaining paths to stop him scoring a stunning political comeback in America's brutally tense presidential election.

Trump's Republican Party also seized control of the Senate, flipping two seats to overturn a narrow Democratic majority.

The Republican former president, 78, won North Carolina, then the second swing state of Georgia, and then the third one: Pennsylvania.

Democratic vice president Harris appeared to be underperforming in key areas compared to Trump as partial vote counts came in.

Her campaign said she would hold off from speaking to supporters at a watch party in Washington, DC, as had been expected earlier.

Harris's camp said the race was now "razor-thin" and that her "clearest path" to victory was through the so-called Blue Wall swing states of Michigan, Pennsylvania and Wisconsin.

Her campaign director Jen O'Malley Dillon insisted in an email to campaign staff, obtained by AFP, that "we feel good about what we're seeing" in the Blue Wall.

Trump spokesman Jason Miller said the mood in the Republican's camp in Florida was "positive."

The US dollar surged and bitcoin hit a record high while most equity markets advanced as traders bet on a victory for Trump as the results rolled in.

Trump's early wins included the reliably Republican Florida and Texas while Harris won California, giving Trump 243 electoral votes and Harris 194. The magic number to win the presidency is 270.

Mood shift

The mood shifted sharply at Harris's watch party in Howard University in Washington -- her former college and a historically Black university -- as the results came in.

Excitement faded and people began to leave, while others stared intently at screens showing the news.

"I am scared," said Charlyn Anderson, who was leaving Howard. "I am anxious now. I am leaving, my legs can barely move."

In contrast, the atmosphere at Trump's Mar-a-Lago resort in Florida and the watch party his campaign was holding in Palm Beach was increasingly celebratory.

Tech tycoon Elon Musk, who has backed Trump, posted a picture of himself with the Republican at Mar-a-Lago.

"Game, set and match," Musk said on X, the social media network he owns.

Millions of Americans had lined up throughout Election Day -- and millions more voted early -- in a race with momentous consequences for the United States and the world.

They were deciding whether to either hand a historic comeback to Trump and his right-wing "America First" agenda or make Harris the first woman in the world's most powerful job.

In a stark reminder of the tension -- and fears of outright violence -- dozens of bomb threats were made against polling stations in Georgia and the crucial swing state of Pennsylvania.

The FBI said the threats appeared to originate in Russia, which is accused by Washington of trying to meddle in the election. The threats were all hoaxes but succeeded in disrupting proceedings.

Oldest president in history

Earlier, Trump -- who has still refused to accept his 2020 election loss, after which his supporters attacked the US Capitol -- added as the first results came in that "we're going to have a big victory tonight."

Polls for weeks had shown a knife-edge race between Harris and Trump, who would be the oldest ever president at the time of inauguration, the first felon president, and only the second in history to serve non-consecutive terms.

Harris, 60, is aiming to be only the second Black and first person of South Asian descent to be president.

She made a dramatic entrance into the race when Biden dropped out in July, while Trump -- twice impeached while president -- has since ridden out two assassination attempts and a criminal conviction.

Trump has vowed an unprecedented deportation campaign of millions of undocumented immigrants, in a campaign full of dark rhetoric.

Harris has hammered home her opposition to Trump-backed abortion bans -- a vote-winning position with women.

The election is being watched closely around the world including in the war zones of Ukraine and the Middle East, anxious to see how the next Oval Office occupant deals with the conflicts.

© Agence France-Presse By Danny Kemp with Anuj Chopra in Atlanta, Georgia