LAS VEGAS (AP) — Critical races in Nevada, including one that could determine control of the U.S. Senate, were too early to call amid a plodding vote count that includes more than 100,000 ballots still to count that were delivered at drop boxes on Election Day and sent by mail.

Sen. Catherine Cortez Masto, a Democrat, was trailing in her effort to fend off a challenge from Republican Adam Laxalt. Democratic Gov. Steve Sisolak was also in a tight race for reelection against Las Vegas-area Sheriff Joe Lombardo, who was also leading Wednesday, and three House seats are in limbo.

With so many drop-box and mail-in ballots still to be counted, both Republicans and Democrats in the high-profile Senate and governor's races have urged supporters to be patient. County election clerks will count mail ballots received until Nov. 12 as long as they were postmarked by Election Day. Officials have until Nov. 17 to finish the counting and submit a report to the Nevada secretary of state’s office, according to state law.

Voting officials in the two most populous counties, encompassing the population centers of Las Vegas and Reno, warned it would take days to process the outstanding ballots.

Officials in Clark County, home to nearly three-quarters of the state's population, reported late Wednesday that 56,900 ballots were collected from drop boxes on Election Day. Registrar of Voters Joe Gloria had reported that every vote cast in person on Tuesday had been counted except for 5,555 provisional ballots that still need to be reviewed.

And more ballots are pouring in. The county received nearly 15,000 ballots Monday and Tuesday that will be counted Wednesday and another 12,700 arrived by mail on Wednesday that won’t be counted until at least Thursday.

Hundreds of staff are working to process ballots as quickly as possible, and “every piece of equipment that we have available to process mail will be in use,” Gloria said.

The counting will continue through Veteran’s Day and the weekend. For any ballots that need a “cure” — which can occur if the signature on the ballot envelope doesn’t appear to match the voter’s signature on file — voters will have until the close of business on Monday to fix the matter, Gloria said.

“There’s no holidays for us,” Gloria said.

There were also thousands of votes to be counted in Nevada’s second most-populous county, where Washoe County interim registrar Jamie Rodriguez said about 4,000 mail-in ballots were received Wednesday — more than anticipated — in addition to the 18,000 received Tuesday.

Rodriguez said she expected significant vote counts to come Thursday.

“Our message to the public is: ‘We are working on it. Please be patient. We want to do it right. We don’t want to do it fast, we want to do it right,’” Rodriguez said.

By Wednesday afternoon, only one of four Nevada House races had been decided. Six-term Republican Rep. Mark Amodei easily defeated Elizabeth Mercedes Krause in Nevada’s rural northern district where no Democrat has ever won.

The 2nd Congressional District was considered the only safe seat for either party among the four in the western battleground of Nevada, where three incumbent Democrats faced stiff challenges.

Nevada is a key national battleground state that former President Donald Trump failed to carry in 2016 or 2020. President Joe Biden defeated Trump two years ago by a slim 2.4 percentage points. While voters in 15 of the state’s 17 counties are reliably Republican, Clark County is largely Democratic.

In rural Nye County, where the interim clerk had embraced a controversial plan to hand-count all paper ballots in response to election conspiracies related to mistrust in voting machines, officials planned to resume hand-counting Thursday after being ordered to stop ahead of Election Day.

Nye County used Dominion voting machines to count and certify its election results. Interim clerk Mark Kampf acknowledged that it would be a tight turnaround, saying the state’s Nov. 17 deadline “does not leave us much time.”

Election Day was marked more by bad weather than reports of voter intimidation.

In Washoe County, Rodriguez said there was one case of voter intimidation, when two men threatened poll workers and were “aggressive” toward voters, before a poll manager escorted them out. The Washoe County Sheriff’s Office said it was investigating.

“It was a lot of comments about them not being patriots, not doing the right thing,” Rodriguez said.

In Clark County, one man walked into a polling place and raised his voice at poll workers, saying the machines were rigged, according to Clark County School District Police Department spokesperson Bryan Zink. Poll workers told him to quiet down before he walked outside, where he tried to pull down the “vote here” sign.

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Boone reported from Boise, Idaho. Associated Press editor Juliet Williams and correspondent Scott Sonner in Las Vegas and writer Gabe Stern in Reno, Nevada, also contributed to this story.

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