The National Republican Senate Committee and Montana Senate candidate Matt Rosendale both compared the poster to the now-infamous photo of the comedian Kathy Griffin holding a fake decapitated Trump head.
The band was traveling Wednesday and not immediately available to confirm whether the skeleton is meant to be Trump.
The rock group’s Twitter account says the official poster from the rock group’s Missoula, Montana, show Monday is a collaboration between bassist Jeff Ament and artist Bobby Brown.
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The band used the show to support the re-election of Rosendale’s opponent, Democratic U.S. Sen. Jon Tester of Montana, who is from Aments’ hometown.