It's official: Joe Biden has been elected the 46th president of the United States

Nearly four days after polls closed across the country, former Vice President Joe Biden has been elected the next president of the United States, ousting President Trump in a harrowingly close election that has pulled the country into wild, uncharted political territory.

On Saturday morning, the Associated Press announced the news that Biden had won Pennsylvania, securing the 270 electoral votes needed to declare victory. "America, I'm honored you have chosen me to lead our great country," Biden wrote on Twitter after the results were announced.

Biden essentially cemented his lead after early morning ballot drops on Friday showed him pulling ahead in both Pennsylvania and Georgia — two must-win states for the Trump campaign. Coupled with expected wins in Nevada and Arizona, the Biden campaign effectively blocked the president's already-narrow path to victory by sweeping a number of states it could have afforded to lose.

Despite the electoral finality of the race, the Trump campaign pointedly refused to admit their loss Friday, issuing a defiant statement that "the election is not over."

The statement, full of oblique references to unfounded allegations of voter fraud in a number of states Trump had lost, followed the president's downbeat, rambling press conference on Thursday night, during which a decidedly exhausted, unenthusiastic-sounding Trump insisted falsely that he was the winner and repeated his hopes that the Supreme Court would simply award him a second term.

And here we enter the uncharted, and much-worried-over interim period of the 2020 election — a stretch of months in which it seems increasingly likely that Trump will simply refuse to concede to Biden, and do his utmost to sow chaos at every opportunity. To what end? It's unclear. While some in the Trump administration have predicted a "peaceful transition" of power, the president's own children have spent the past few days ratcheting up their baseless allegations of electoral theft, with Donald Trump Jr. at one point echoing Nazi propagandist Joseph Goebbels's infamous call to declare "total war" on his enemies.

Despite Trump and his allies' chaotic saber-rattling, the Biden team has already begun moving ahead with plans for the transition of power, declaring in a statement after the president's refusal to concede that "the U.S. government is perfectly capable of escorting trespassers out of the White House."