A tense US presidential election was still undecided on Wednesday, even as Democratic candidate Joe Biden's path to the White House became clearer with projected wins in Wisconsin and Michigan - two vital swing states captured by President Donald Trump in 2016.
Biden expressed confidence in winning the race, while President Donald Trump sought to undermine the integrity of the election and claimed victory in states that are too close to call, or have been called for Biden.
The Trump campaign said it will seek a recount in Wisconsin, where Biden currently holds a narrow 20,000-vote lead out of over 3.2 million counted in the state.
The campaign is also mounting legal challenges in Pennsylvania, Michigan, and Georgia over vote counts - indicating that they have no plan to concede in the near term.
"It's clear that we're winning enough states to reach 270 electoral votes needed to win the presidency," Biden said in Delaware, while stressing that he is not yet claiming victory.
"When the count is finished, we believe we will be the winners."
The Democrat insisted "every vote must be counted" and that no one can simply seize a win by making declarations, a dig at Trump.
Key swing states
The key swing states of Wisconsin, with 10 electoral votes, and later Michigan, with 16, were called for Biden by networks on Wednesday afternoon.
If Biden can hold Michigan and Wisconsin he only needs one more state to win a majority of the Electoral College, giving him the presidency.
Trump on the other hand is increasingly facing an uphill battle and enters a situation where nearly every remaining state is a must-win.
The country is now anxiously awaiting more vote tallies in Nevada, where Biden leads by a slim margin, and Georgia, North Carolina, and Pennsylvania, where Trump holds leads.
In Pennsylvania, a populous state that could end up the decisive one, one lawsuit launched by Trump's campaign seeks to temporarily halt ballot counting in the state.
Pennsylvania Governor Tom Wolf earlier said the state's outcome might not be known on Wednesday as "millions of mail-in ballots" were still being counted.
"We may not know the results even today, but the most important thing is that we have accurate results, even if that takes a little longer than we're used to," Wolf, a Democrat, told a press conference.
It remains unclear who will win the Pennsylvania when all of the votes are tallied. Many Republicans chose to vote in-person, while Democrats embraced mail-in ballots which have yet to be fully counted.
Meanwhile Biden leads Nevada by less than 8,000 votes as local authorities are expected to release a large tranche of ballot counts around Las Vegas on Thursday.
Early leads can often be reduced or overturned, depending on which counties in any state report first and how postal ballots are tallied.
Earlier, Trump claimed without evidence that a lead he claimed he had in several key states had "magically" disappeared overnight.
"Last night I was leading, often solidly, in many key states, in almost all instances Democrat run & controlled. Then, one by one, they started to magically disappear as surprise ballot dumps were counted," he tweeted, in another post flagged by Twitter.
In an overnight speech, Trump said - again without offering proof - that there was "major fraud" under way and threatened to take the fight for the election to the courts.
At around the same as Trump tweeted, Biden urged patience, writing on Twitter: "We won't rest until everyone's vote is counted."
Turnout this year, as a percentage, has been higher than any other election since 1900.
Supreme Court
In his early-morning speech, Trump threatened to turn to the Supreme Court and said he wanted "all voting to stop," but it was not clear exactly what he hoped to accomplish.
States run elections and Trump would have to first go through lower-level courts.
Biden's team said it had lawyers ready to fight back.
Both candidates' campaigns were asking supporters for money to fund the legal battles, with Biden saying he was "setting up the largest election protection effort ever assembled."
The Democratic nominee has kept his cool throughout the nail-biter of an election while Trump has thrown the country into a state of uncertainty by appearing to declare himself the victor.
In stark contrast to the tone struck by Trump, Mitch McConnell, the top Republican in the Senate, on Wednesday said the election result had not been decided.
"We are awaiting the judgement of the American people," McConnell told reporters in his home state of Kentucky.
McConnell, who won re-election, said it was also unclear if his party would maintain its majority in the upper chamber of Congress, though Republicans beat back Democrats in key Senate races.
Democratic lawmaker Nancy Pelosi, the leader of the House of Representatives, said Biden's path to the White House is "clear."
"Joe Biden’s election will be historic, propelled by the votes of a record-shattering 70 million Americans - the most votes ever received by a presidential ticket in American history," Pelosi said.
