Joe Biden secured enough votes in the US electoral college at 11.25am EST on Saturday to become the 46th president of the United States. The Democratic nominee crossed the 270-vote threshold by winning the state of Pennsylvania after a long and drawn-out counting process exacerbated by a large number of mail-in ballots. It was a dramatic turnaround from early on election night, when Republican incumbent Donald Trump looked likely to sweep the race, taking the swing state of Florida. Mr Trump’s campaign is still set on a series of legal challenges over alleged irregularities in the electoral process in several states. Mr Biden was also leading Mr Trump in Arizona, Georgia and Nevada, where votes are still being counted, but it was Pennsylvania’s 20 electoral votes that pushed him over the 270-vote threshold in the electoral college to win the presidency. Reacting to his victory, Mr Biden repeated his vow to work for all Americans. “America, I’m honoured that you have chosen me to lead our great country,” the president-elect wrote on Twitter. “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.” Mr Trump has refused to accept the election results, continuing to repeat his false claims of voter fraud with mail-in-ballots despite zero evidence of fraudulent ballots. Shortly before Mr Biden’s win, he again asserted his claim to have won the vote, tweeting: “I won this election, by a lot!” He first claimed to be headed for victory early on election night, tweeting: “We are up BIG, but they are trying to STEAL the Election,” a missive both Facebook and Twitter hid behind labels telling users it was potentially misleading. In a later speech, he said he would seek the US Supreme Court to stop the vote count for early ballots in key states where he led the race. “We want all voting to stop. We don’t want them to find any ballots at four o’clock in the morning and add them to the list,” he said. Mr Trump had continued to insist that the winner of the election should be announced on November 3 even if all the ballots had not been counted. On Saturday, his lawyers told a press conference in Philadelphia that “Beginning Monday, our campaign will start prosecuting our case in court to ensure election laws are fully upheld and the rightful winner is seated.” Mr Trump campaigned by doubling down on the culture war issues that propelled him to the White House in 2016. He touted his hard-line immigration policies and campaigned as the “law and order” candidate, hoping to capitalise on white voters’ resentment and fear of the increased Black Lives Matter protests and sporadic riots that swept the country in late spring following numerous police shootings of black Americans. By contrast, Mr Biden campaigned by appealing to centrists, independent swing voters and Republicans disaffected with Mr Trump’s presidency. He leaned heavily into his criticism of Mr Trump’s handling of the coronavirus pandemic, which has killed more than 240,000 Americans to date ahead of another expected spike in the cold winter months. At the same time, the Biden campaign has adopted policy platforms meant to assuage and bolster support among the party’s left flank. While he made some concessions to his chief primary opponent Bernie Sanders on issues such as climate change and health care, it remains to be seen whether Mr Biden will pursue a more progressive agenda or govern strictly from the centre as he tries to combat the pandemic and jumpstart the flagging economy which has left about 12.6 million Americans unemployed. But it remains unclear whether Democrats will be able to take control of Congress, threatening more gridlock between a Biden White House and a Republican-held Senate. Democrats maintained control of the House of Representatives but the outcome in the Senate is in limbo until January, and there’s a good possibility that it will remain in Republican hands. Mr Biden was the vice president under Barack Obama from 2009 to 2017. Prior to that he served as the US senator from Delaware between 1973 and 2009. His running mate, Kamala Harris, is slated to become the first US female vice president, as well as the first black and South Asian person to hold the office.