But Boulware said he won't issue a final ruling until a hearing Friday afternoon about whether another defendant, Roger Stone Jr., and his group called "Stop the Steal" are encouraging what Democrats call "vigilante voter intimidation."
Similar claims have been made in lawsuits filed in Ohio, Pennsylvania and Arizona, where a similar hearing was being held Thursday.
Boulware's comments came after Nevada's top Trump election-day operations chief testified that on Thursday morning he sent emails to the more than 100 people he had trained as poll-watchers about rules they have to follow if they challenge a voter's eligibility.
The judge acknowledged that Trump campaign official Jesse Law's emailed instructions essentially pre-empted the remedy he would have considered if he found evidence of intentional omissions in training for poll-watchers.
"There doesn't seem to be a basis at this point to issue a temporary restraining order," Boulware told attorneys for the state Democratic party and a lawyer representing both the Nevada Republican Party and the Trump campaign.
He also told attorneys for the Democratic and Republican parties that he wasn't convinced there was a firm link between Trump and Stone or between the campaign and the state party.
But in a nod to what the judge called "unique and special enthusiasm in this election," he said he'll keep time open Tuesday to hear any reports that might emerge about voter harassment at the polls.
The lawsuits in Nevada, Arizona, Ohio and Pennsylvania target state Republican parties, Trump's campaign, Stone and "Stop the Steal," which is organizing what it calls "citizen journalists" and "poll watchers."
The Trump campaign says the lawsuits are long on rhetoric and short on substance and designed to distract from Democratic candidate Hillary Clinton's troubles.
In Phoenix, attorneys for Trump and the state GOP want U.S. District Court Judge John Tuchi to reject what they called an emergency request to prohibit hypothetical political conduct by unidentified people.
Tuchi was set to hear from both sides in the case. It was unclear when he would rule.
The lawyers said the Democrats are citing "opaque remarks in public speeches by political candidates as the basis for four cookie-cutter lawsuits filed across the country to garner headlines and cause chaos in the efforts of their political opponents."
Republican court briefings also say there's no evidence that any intimidation is happening. State and federal laws already bar intimidation and the Democrats are asking for orders that would unconstitutionally bar protected political speech, the documents state.
The Democrats allege that Trump's calls to supporters to show up at the polls to prevent voter fraud is a call to illegal intimidation tactics. They say Stone is organizing volunteer poll watchers to confront voters.
The lawsuits cite provisions of the Ku Klux Klan Act of 1871 and the Voting Rights Act of 1965 that prohibit intimidating or threatening voters.
Ritter reported from Las Vegas.
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