By Stephanie Becker, CNN

(CNN) -- A Nevada judge rejected a GOP lawsuit seeking to halt early vote counting in Clark County, which includes Las Vegas, over stringency of signature-matching computer software and how closely observers can watch votes being counted.

With less than 24 hours before Election Day, District Court Judge James Wilson denied the Nevada Republican Party and the Trump campaign their request challenging procedures for poll observation and mail-in ballot processing in heavily Democratic Clark County.

President Donald Trump has consistently criticized Nevada Gov. Steve Sisolak, a Democrat, for the decision to send ballots to all active voters because of the pandemic, and the battleground state is one of several where Republicans have tried to limit mail-in voting activity.

Roughly 70% of Nevada's voters live in Clark County.

Nevada Republican Party Chairman Michael McDonald called the ruling a "dark day in our state's history, but our fight for a free, fair and transparent election is not over." He said the party has not yet decided if they will appeal to the Nevada Supreme Court.

Lawyers for the Trump campaign claimed that their observers were not given enough access to all aspects of the ballot counting process -- from opening the ballots, to machine and manual signature checking and duplicating spoiled ballots.

A half dozen Republican observers testified, including one man who came from New Jersey whose travel was paid for by the Trump campaign. Another Trump campaign observer, a nurse, testified that from her angle, she could see a signature match that should not have been approved. A lawyer for the state questioned her credentials as a handwriting expert. Others testified that ballots were taken behind closed doors to areas they could not see. But none of them testified that they had seen fraudulent behavior.

Republicans asked the judge that they be able to install their own cameras to cover all aspects of ballot processing. In his plea to Wilson, Republican attorney Jesse Binnall said, "All we're asking for is some meaningful way to observe this process, some meaningful way also to observe the signature matching process."

Clark County Registrar of Voters Joseph Gloria defended the process, adding the pandemic required distancing observers from workers. Gloria also told the judge that his department has complied with the law and any changes to the system now would put the counting of ballots in jeopardy.

Republicans wanted Wilson to put a halt to the use of the signature reading machine called the Agillis. Gloria noted that despite using the signature reading machine, 70% of signatures were matched manually by humans. He also testified that he feared that without the machine there would no way his department could count the 1 million-plus ballots in time.

Mary-Anne Miller representing Clark County summed up by saying "All of the evidence that they have submitted today is speculative. They have not identified any error of any fraud that's taking place on behalf of any voter."

Monday, Wilson ruled that the Republicans had "failed to prove they have standing to bring their Agillis (the signature matching software), observation, ballot handing or secrecy claims." He further stated that there was no evidence that any harm had been caused by Clark County's procedures and that Gloria had fulfilled his legal duty.

This story has been updated with details from the ruling and background.