Joe Biden has vowed to unite people in a deeply divided nation as the next United States president, after a marathon election campaign marked by heated rhetoric.

In his first address since defeating Donald Trump to win the White House, Biden said he intends to govern for everyone – and praised the broad range of support he received from people across the country who voted for him in record numbers.

“Folks, the people of this nation have spoken. They delivered us a clear victory, a convincing victory, a victory for ‘We the people’,” the Democratic president-elect told a crowd of supporters at a rally in his hometown of Wilmington, Delaware on Saturday night.

Thousands joined the physically distanced car rally in Wilmington, cheering and waving US flags and Biden-Harris 2020 posters.

“I pledge to be a president who seeks not to divide, but unify; who doesn’t see red states and blue states – only sees the United States – and who will work with all my heart to win the confidence of the whole people,” Biden said.

After several days of waiting for a winner to be declared in the tightly contested presidential race, which pit Biden against incumbent President Trump, the Associated Press news agency on Saturday morning projected that Biden had won the White House.

The former US vice president had urged calm this week as several key states continued to count ballots, while projecting confidence that he and vice-presidential running mate Kamala Harris would ultimately be declared the winners.

With the victory, Harris becomes the first Black woman and person of Asian descent to be named vice president-elect.

“While I may be the first woman in this office, I will not be the last. Because every little girl watching tonight sees that this is a country of possibilities,” said Harris, who took the stage in Delaware before Biden.

“When our very democracy was on the ballot in this election, with the very soul of America at stake, and the world watching – you ushered in a new day for America,” she told the crowd, thanking Americans for choosing “hope and unity, decency, science and yes, truth”.

“You chose Joe Biden as the next president of the United States of America,” she said to applause and honking horns.

‘Election far from over’

Trump has not conceded the race, saying earlier on Saturday that “this election is far from over” and vowing to legally challenge the results in several states.

The Republican leader has repeatedly said – without providing any evidence – that widespread voter fraud has marred the election.

Experts have rejected those allegations as baseless , though many of Trump’s supporters have echoed them in protests denouncing Biden’s victory.

The president’s supporters have held rallies in Wisconsin, where the Trump campaign has said it intends to demand a recount due to the small margin of victory Biden recorded there, as well as in Arizona, Georgia and Pennsylvania, which also saw tight races.

“Beginning Monday, our campaign will start prosecuting our case in court to ensure election laws are fully upheld and the rightful winner is seated,” Trump said in his statement. Healing divisions

Biden and Harris will need to heal a deeply divided country, which has experienced mass racial justice protests for months and has been devastated by the deadly COVID-19 pandemic.

“There is going to be an enormous task at hand for this Democratic ticket as it assumes the White House,” Al Jazeera’s Kimberly Halkett reported, “trying to unite Americans and to win over the support of the millions of Americans who did no vote for them.”

That was a chief theme in Biden’s speech, in which he took a brief moment to speak directly to Trump supporters.

“I understand the disappointment tonight,” he said. “I’ve lost a couple times myself, but now let’s give each other a chance. It’s time to put away the harsh rhetoric, lower the temperature, see each other again, listen to each other again.”

Meanwhile, across the country, Biden supporters have been celebrating.

Thousands of people joined boisterous rallies in numerous cities throughout the day on Saturday, from New York to Philadelphia, North Carolina, Minnesota, and Georgia, as well as out in front of the White House in Washington, DC.

A lively crowd of people in the US capital, most of whom wore masks due to the COVID-19 pandemic, danced, played music and drank champagne. “I was getting ready for this day for a long time,” Andrew Hasson told Al Jazeera from the rally.

“This week was super stressful just waiting for the results to come in, but this is a great feeling and DC feels alive again.”