LAS VEGAS — Clark County election officials said Wednesday they are still days from completing ballot counting in the state’s largest county, leaving up in the air the results of a contest that could determine control of the U.S. Senate. 

Elections officials here have counted and posted the in-person votes cast on Election Day, said Clark County Registrar Joe Gloria, but are still sorting through tens of thousands of ballots that have come through the mail and were left in drop boxes. In Nevada, mail ballots postmarked by Nov. 8 can arrive through Saturday and still be counted.

Just under 15,000 ballots will be processed throughout the day and reported tonight, Gloria said at a news conference. He added that he expects the county to update vote totals once a day. 

The counting continues as Democratic Sen. Catherine Cortez Masto is attempting to cling to her seat as Republican Adam Laxalt ran up sizable margins in the state’s 15 rural counties. With 80% of expected votes in, NBC News’ latest tally shows Laxalt at 418,461 votes statewide to Cortez Masto’s 395,866.