Democrat Joe Biden has won the White House, US media said on Saturday, defeating Donald Trump and ending a presidency that convulsed American politics, shocked the world and left the United States more divided than at any time in decades.

The confirmation of victory of Biden, who at 78 will be the oldest American president, brings to a climax three days of post-election anxiety and uncertainty that followed one of the most bruising US presidential races in modern times.

The Associated Press declared Biden, whose vice president will be Kamala Harris — the first female to hold the post in America's history, the winner on Saturday evening after he secured more than the crucial 270 electoral votes he needed to win the White House.

CNN, NBC News and CBS News also called the race in his favour, after projecting he had won the decisive state of Pennsylvania. Shortly after winning the presidency, Biden also won Nevada, adding to his Electoral College victory over Trump.

Biden declared victory in a tweet, saying: "America, I’m honored that you have chosen me to lead our great country.

Profile: Shaped by tragedy, Joe Biden eyes calm after Trump storm

"The work ahead of us will be hard, but I promise you this: I will be a President for all Americans — whether you voted for me or not. I will keep the faith that you have placed in me."

Trump, refusing to concede defeat, said that Biden was “rushing to falsely pose as the winner” after television networks declared the Democrat's victory.

“We all know why Joe Biden is rushing to falsely pose as the winner, and why his media allies are trying so hard to help him: they don't want the truth to be exposed,” Trump said.

“The simple fact is this election is far from over.”

Trump underlined that states had not yet certified the results, and his campaign has launched multiple legal challenges.

However, near complete results issued by each state showed an insurmountable lead for Biden, allowing network news channels to call the overall result, as they do every election.

In a tweet, Harris said the election was about "so much more than [Biden] or me. It’s about the soul of America and our willingness to fight for it. We have a lot of work ahead of us. Let’s get started."

Prime Minister Imran Khan congratulated Biden and Harris in a tweet for making it to the White House.

"Congratulations @JoeBiden & @KamalaHarris. [I] look forward to President Elect Biden's Global Summit on Democracy and working with him to end illegal tax havens and stealth of nation's wealth by corrupt leaders," he wrote.

The premier said Pakistan "will also continue to work with US for peace in Afghanistan and in the region".

For Biden, who got more than 74 million votes, a record, the triumph after a tense contest conducted during a global coronavirus pandemic was the crowning achievement of his half century in US politics, including eight years as deputy to the first Black US president Barack Obama.

The result condemned 74-year-old Trump — who made frantic attempts to claim fraud and stop the vote count — to becoming the first one-term president since George H. W. Bush at the start of the 1990s.

The Republican, whose marathon press conferences, tweeting and raucous campaign rallies have made him a perpetual, noisy presence at home and abroad over the last four years, had no immediate reaction.

But ever since the night after Tuesday's election, when he prematurely claimed victory, Trump has been inhabiting a world increasingly disconnected from the reality of his approaching downfall.

Earlier on Saturday, he left the White House for the first time since Election Day to play golf, tweeting: “I WON THIS ELECTION, BY A LOT!”

And in an extraordinary White House address to the nation on Thursday — with Biden's lead in the partial results already consolidating rapidly — he claimed “they are trying to steal the election.” Despite Trump's protests, the returns from vote counting offices around the country kept coming all week, with no credible reports of irregularities.

And when US television networks declared that Biden had taken an insurmountable lead in Pennsylvania, that put the Democrat over the magic number of 270 Electoral College votes. Trump had no way back.

Biden's path to 270

As Americans remained glued to TV screens and their phones and the world awaited an announcement with bated breath after polls closed on Tuesday, Biden ended up securing victories in the “blue wall” battlegrounds of Wisconsin and Michigan and narrowing Trump’s path to reelection.

But with just a handful of states still up for grabs, Trump tried to press his case in court in some key swing states. In spite of the aggressive Republican move, the flurry of court action did not seem obviously destined to impact the election’s outcome.

Two days after Election Day, neither candidate had amassed the votes needed to win the White House. But Biden’s victories in the Great Lakes states left him at 264, meaning he was one battleground state away — any would do — from becoming president-elect.

Trump, with 214 electoral votes, faced a much higher hurdle. To reach 270, he needed to claim all four remaining battlegrounds: Pennsylvania, North Carolina, Georgia and Nevada.

With millions of votes yet to be tabulated, Biden already had received more than 71 million, the most in history. At an afternoon news conference on Wednesday, the former vice president said he expected to win the presidency but stopped short of outright declaring victory.

“I will govern as an American president,” Biden said. “There will be no red states and blue states when we win. Just the United States of America.”

Who is Joe Biden?

With decades of political experience under his belt, this was Joe Biden's third run at the White House.

Born in Scranton, Pennsylvania, the 77-year-old began his political career in 1972, when he was first elected to the US Senate from Delaware state. The Democrat has considerable experience in foreign policy and was the chair of the Senate Foreign Relations Committee twice in his career. He has also served as the chairperson of the Committee on Judiciary.

Though long and distinguished, Biden's career is certainly not stain-free. He has faced criticism for sponsoring the Violent Crime Control and Law Enforcement Act of 1994, which critics say led to the mass incarceration of African Americans.

The former vice president is also no stranger to personal loss and tragedy. In 1972, he lost his wife and baby daughter in a car accident soon after he won his first seat in Senate. His sons Beau and Hunter survived and Biden swore his oath while in the hospital with his sons.

In 2015, when Biden was vice president, his son Beau died from brain cancer. He was 46 and had started off a career in politics.

Biden first ran for president in 1988 but withdrew from the race after it was revealed that he had plagiarised a speech from Neil Kinnock, then leader of the British Labour Party.

He tried his luck once again in 2008 but was unsuccessful this time too as the Democratic Party nominated Barack Obama. Biden was later nominated for the position of vice president and served alongside Obama for the next eight years.

Biden, who mocks Trump's 'America First' slogan as 'America Alone', aims to restore the country's position as a global leader.

Header image: Democratic presidential candidate Joe Biden speaks to supporters, early Wednesday, Nov 4, in Wilmington, Delaware. — AP