Joe Biden has promised to be a “President for all Americans” after topping the 270 electoral college votes needed for victory over Donald Trump in the US presidential race.

The former vice-president was called as the winner of Pennsylvania on Saturday, meaning he has an insurmountable lead in the race for the White House.

Mr Biden said he is “honoured” that America has “chosen me to lead our great country”, adding that it is time for the US to “unite” and “heal”.

Winning the vote in Wisconsin, Michigan and Arizona – three states that voted for Mr Trump in 2016 – opened up several pathways to the presidency for the Democratic candidate.

It was victory in Pennsylvania, some four days after polls closed that saw him over the line.

A little earlier, Mr Trump, who has yet to concede, left the White House reportedly to play golf.

Mr Biden said on Twitter: “America, I’m honoured that you have chosen me to lead our great country.

“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.”

In a statement, Mr Biden said: “I am honoured and humbled by the trust the American people have placed in me and in Vice President-elect Harris.

“In the face of unprecedented obstacles, a record number of Americans voted. Proving once again, that democracy beats deep in the heart of America.

“With the campaign over, it’s time to put the anger and the harsh rhetoric behind us and come together as a nation.

“It’s time for America to unite. And to heal.

“We are the United States of America. And there’s nothing we can’t do, if we do it together.”

Mr Trump made a series of unsubstantiated allegations to claim he is being cheated out of re-election, while Mr Biden had called for calm as votes in key battleground states were counted well past November 3.

On Saturday morning, a top election official dismissed Mr Trump’s fresh claims of voter fraud.

Mr Trump posted a number of tweets on Saturday, alleging that “bad things” happened, referring to votes being “illegally received” and insisting he has won “by a lot”.

But Federal Election Commission commissioner Ellen Weintraub said there has been no evidence of voter fraud.

Speaking on CNN after Mr Trump’s string of tweets – which were flagged by Twitter as containing information about the election that may be “misleading” – Democrat Ms Weintraub said: “State and local officials, and poll workers throughout the country, really stepped up.

“And there have been very few complaints about how this election has run.

“Very few substantiated complaints, let me put it that way. There is no evidence of any kind of voter fraud.

“There is no evidence of illegal votes being cast.

“In fact, and you don’t have to take my word for it because people throughout the country, non-partisan election experts have come out and hailed this election and how it was run.

“If you want to look at the state of Pennsylvania, which the president seems to be focused on, Senator (Pat) Toomey has come out and said he has seen no evidence of fraud there.

“The Republican leader of the state senate there has also said he has seen no evidence of fraud.”

She added: “There really has been no evidence of fraud. None of the complaints have attached any evidence of fraud.

“Really, we should feel very proud of ourselves.”

Her comments came after Mr Trump wrote on Twitter that tens of thousands of votes were “illegally received” after 8pm on Tuesday “totally and easily changing the results in Pennsylvania and certain other razor thin states”.

Mr Trump said there will be a “big press conference” in Philadelphia on Saturday afternoon UK time, adding on Twitter: “I WON THIS ELECTION, BY A LOT!”

Twitter flagged this tweet, saying official sources may not have called the race when it was tweeted.