Montana Republicans seeking to prevent non-GOP voters from participating in their primary elections are making a long-shot appeal to the U.S. Supreme Court.

Friday's emergency application for an injunction comes after the 9th U.S. Circuit Court of Appeals denied a similar request this month ahead of the June 7 primaries.

Attorney Matthew Monforton says the petition is the GOP's last chance to close this year's primaries. He says they will have to prepare for trial if the high court denies the application.

Montana law allows voters to fill out either a Republican or a Democratic ballot in primary elections.

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