Trump and his party argued that the ballots should not be counted until they are allowed to observe the process, according to AP.
The incumbent President and his party alleged that the county, which covers Las Vegas, refused to comply with extensive public record requests relating to signature verification on mail-in ballots.
However, all seven members of the State Supreme Court signed an order rejecting the appeal.
But the judges, however, set an expedited briefing schedule to allow the Trump campaign organization and state Republicans to file a formal brief arguing their case.
The officials, who are the defendants, were also given until Monday to respond.
Also 30 polling sites were ordered to stay open for an extra hour after Trump’s team argued that they opened late to voters.
Nevada remains a battleground and Trump is fighting hard to win despite that no Republican presidential candidate has won Nevada since 2004.