While no winner has been projected, Biden entered Saturday with higher vote totals in four key states: Arizona, Georgia, Nevada and Pennsylvania. But all four remained rated by the NBC News Decision Desk as too close to call.
A call in both Nevada and Arizona in Biden's favor would put him right at the 270 electoral votes needed to win, while a victory in Pennsylvania alone would give him 273 electoral votes.
As Americans watched as the vote count entered the fourth day, Democrats have tried to project optimism.
“We don’t have a final declaration, a victory yet. But the numbers tell us a clear and convincing story,” Biden said in a brief speech Friday night. “We’re going to win this race.”
Trump and his campaign are vowing to fight even if Biden is declared the winner, looking to launch a multi-front legal battle to overturn votes they claim should not be tallied. The campaign has failed to provide any evidence of the wide-scale voter fraud they claim is running rampant in places like Philadelphia.
"Joe Biden should not wrongfully claim the office of the President," Trump tweeted on Friday night. "I could make that claim also. Legal proceedings are just now beginning!"
Trump, who has not addressed the country in person since Thursday night, arrived at his Virginia golf course Saturday morning.
Trump has repeatedly and erroneously declared victory, including in states where Biden is the projected winner. The president has also repeated unfounded conspiracy theories and tried to cast doubt on the integrity of the tabulation process.
In Pennsylvania, Biden is leading by over 28,000 votes, 3,336,887 votes (49.6 percent) to Trump's 3,308,054 (49.1 percent), with 96 percent of the expected vote in. Many of the remaining ballots come from Democratic-leaning areas.
Allegheny County, home to Pittsburgh, will resume counting ballots Saturday morning, and the state is expected to continue to slowly report new numbers throughout the day.
In Nevada, Biden leads by just over 22,000 votes, 632,558 votes (49.8 percent) to Trump's 609,901 votes (48 percent), with 93 percent of the expected vote in.
In Arizona, Biden is up a little under 30,000 votes, 1,606,526 (49.5 percent) to Trump's 1,578,563 (48.7 percent), with 97 percent of the expected vote in.
Georgia appears headed for a recount with Biden leading narrowly by about 7,200 votes, 2,461,455 (49.4 percent) to Trump's 2,454,207 (49.3 percent).
Georgia state officials said they anticipate the closeness of the race will result in a recount.