WHY AP HASN'T CALLED NEVADA:

A tight vote margin and large number of ballots that have yet to be counted made the Nevada race between President Donald Trump and Democratic challenger Joe Biden too early to call Friday.

With more than 1.2 million ballots counted, Biden held a 22,657 vote lead Friday evening — a roughly 1.79 percentage point edge over Trump. But even after about 87% of the estimated vote had been tallied, tens of thousands of votes remained to be counted statewide, which could eat into Biden's advantage.

Election officials in the state said they would release more results Saturday at noon EST.

Most of the ballots were in Clark County, home to Las Vegas, a Democratic-leaning area where most of the state's voters live. Biden held a nearly 9 percentage point lead over Trump in the county on Friday. And elections officials there said they plan to continue counting 55,000 mail ballots there over the weekend.

Yet questions remain over just how much of the vote was left to count across the state, including these:

— Clark County officials said Thursday that they would be releasing the results of 51,000 ballots on Friday. But they later clarified that they had overestimated the size of the batch and released results from about 30,000 ballots instead.

— Separately, state officials said Thursday that there were about 190,000 votes left to count statewide, a total that included mail ballots and provisional ballots from voters who registered or updated their registration at the polls. But it was unclear if that figure took into account the overestimated number of ballots by Clark County election officials.

In a tight race, that could delay the AP declaring a winner. For example, in the 2004 race between George W. Bush and John Kerry, the AP did not call the winner of the election in Ohio until it was able to confirm that Bush’s lead exceeded the number of provisional ballots left to be counted.

Nevada, once a swing state, has trended toward Democrats in the past decade. But this year there were signs that Trump could have an opening after narrowly losing the state in 2016.

Overall, Trump performed better than Mitt Romney did in 2012 or John McCain in 2008. The state also has has a higher percentage of non-college-educated whites, who have made up the base of his electoral support, than in many other pivotal states, including Florida, Arizona, Michigan, Pennsylvania and Wisconsin.

Bush was the last Republican to win there, in 2004.