The U.S. Supreme Court and federal judges in three states turned down requests by the Democrats on Monday to head off what party leaders say are plans by Donald Trump's supporters to harass and intimidate voters on Election Day.

The Democrats asked for restraining orders to prevent what they characterized as ballot-box vigilantism by Trump's Republican presidential campaign and his friend Roger Stone's political organization, Stop the Steal.

But the Supreme Court issued a one-page denial in a case out of Ohio, with Justice Ruth Bader Ginsburg noting that state law already forbids voter intimidation. And the Democrats' arguments in federal courts in Pennsylvania, North Carolina and Nevada fell flat in those crucial battlegrounds, too.

Warning repeatedly that the election is about to be stolen from him, Trump has called on his supporters to act as election observers in parts of the country to prevent fraud. That has stirred fears of minority voters being confronted and challenged by self-appointed poll watchers.

In Las Vegas, a lawyer for Stop the Steal promised Monday that volunteers who conduct exit polls will be advised in a last-minute conference call that federal law prohibits voter intimidation.

Attorney Adam Fulton told U.S. District Judge Richard Boulware that an email will tell the 65 or so people planning to visit Nevada polling sites they can't talk with people within 100 feet of a polling place, and can't photograph or use video or audio to record people without that person's permission.

With that promise, the judge declined to issue a temporary restraining order that Democrats had sought in a lawsuit alleging that Stone, the group, the Nevada Republican Party and the Trump campaign plan to harass Nevada voters.

But Boulware said he'll keep time open Tuesday to hear complaints if they arise during morning voting.

In North Carolina, U.S. District Judge Catherine Eagles said she saw insufficient evidence the state's Republicans and Trump want supporters to intimidate minorities on Tuesday. But she said she will keep an eye on the balloting and could revisit the case quickly if there's evidence of a conspiracy to suppress voting.