Timeline: Which states could tip U.S. election and when will they report results?

To capture the White House, a candidate must amass at least 270 votes in the Electoral College. Most major TV networks gave Biden a 253-214 lead in electoral votes on Thursday.

Results in Pennsylvania (20 electoral votes), Georgia (16), North Carolina (15), Arizona (11) and Nevada (6) remained uncertain, according to Edison Research.

ARIZONA

Biden's lead shrank on Thursday night when nearly 74,000 votes were reported from Maricopa County, which includes heavily populated Phoenix. Of those, Trump won 42,276 and Biden 31,700, reducing Biden's lead in Arizona to 50.1% versus 48.5%, with 90% of votes counted.

There were at least 320,000 ballots left to be counted in the state. Maricopa County accounted for over 200,000 of the outstanding ballots, the elections department said.

Trump's lead shrank to 0.1 percentage point on Thursday night, or just 2,497 votes, with 99% of votes reported.

NEVADA

Biden led Trump by 11,438 votes, or 0.9 percentage point, with about 11% of the vote left to be counted.

Nevada Secretary of State Barbara Cegavske said in a statement that about 190,150 ballots remained to be counted in the state, with 123,554 of them being either mail-in ballots or ballots returned at drop-off locations. She said 90% of the ballots still to be counted were in Clark County, the state's largest.

All properly received ballots will be counted for up to nine days after the election, but the exact number left to be counted was unknown, Cegavske said.

The outstanding votes are mail-in ballots and those cast by voters who registered to vote at polling place on Election Day, she said.

Trump led by more than 76,000 votes, or 1.4 points, with about 5% of the vote uncounted.

State officials have said a full result would not be known until next week. The state allows mail-in ballots postmarked by Tuesday to be counted if they are received by Nov. 12.

Trump's lead continued to shrink in Pennsylvania. He led by 0.7 of a percentage point, or 48,854 votes, with 6% of the vote outstanding.

About 370,000 ballots were still in the process of being counted on Thursday, according to the Department of State's website, giving Biden a chance to catch Trump if enough of them were from Democratic-friendly areas such as Philadelphia. Pennsylvania Secretary of State Kathy Boockvar said she expected the "overwhelming majority" to be counted by the end of Thursday.

Philadelphia County reported more than 252,000 ballots were cast by mail but did say how many remained to be counted.

A final count may not be available until at least Friday as Pennsylvania can accept mail-in ballots up to three days after the election if they were postmarked by Tuesday.