Joe Gloria, registrar of voters for Clark County, Nevada, said that of the ballots the county has received, 63,262 have yet to be counted. Biden is leading in the county, which includes Las Vegas, by 431,863 votes to Mr. Trump's 367,279.
Among those, 34,743 were returned by voters to drop-off locations on Election Day. Another 24,311 mail-in ballots were pending as of Election Day, and 4,208 were received from the U.S. Postal Service on November 3 and November 4.
Staff in Clark County are prepared to count 51,000 ballots throughout the day Thursday and results will be reported before 1 p.m. ET Friday, Garcia said. He added that there are more than 60,000 provisional ballots cast during early voting and on Election Day that are outstanding.
Garcia dismissed allegations of voter fraud that have been made by members of the Trump campaign, saying he is "not aware of any improper ballots that are being processed."
"Our goal here in Clark County is not to count fast," he said. "We want to make sure we're being accurate."
Garcia said Clark County is on track to complete the bulk of its mail-in ballot count by Saturday or Sunday.
Earlier Thursday, the Trump campaign announced that it's filing a lawsuit alleging voter fraud, claiming that roughly 10,000 people who cast ballots no longer live in Nevada. At about 1 p.m., Mr. Trump was trailing Biden in the state by about 11,000 votes in the state, and though it's extremely close, he has been slowly falling further behind as more votes are counted.
The campaign is asking a federal district court in Las Vegas for an emergency temporary restraining order "to stop the counting of improper votes."