The National Republican Senatorial Committee (NRSC) criticized Sen. Jon Tester (D-MT) in an ad released Thursday, charging that Tester “showed his true colors by refusing” to condemn a Pearl Jam poster featuring a dead President Donald Trump.

Sen. Tester’s campaign struck controversy last week when a Pearl Jam poster for a get-out-the-vote concert promoting the Montana Democrat featured a dead Donald Trump and an American bald eagle eating the remains of his corpse. Tester is close friends with Pearl Jam bassist Jeff Ament, who designed the poster.

Tester’s campaign, not Tester himself, disavowed the poster, only after the media shed light on the controversy. Two weeks after the literature was revealed, Tester has yet to personally disavow it.

Montana state auditor Matt Rosendale, who hopes to unseat Sen. Tester in the November midterm elections, told Breitbart News Tonight last week he found it “very disturbing” that Sen. Tester has yet to personally condemn the Pearl Jam poster.

Calvin Moore, an NRSC spokesman, said Sen. Tester “showed his true colors by refusing” to condemn the poster and suggested that if the Montana senator will not do the right thing, Montanans should–by voting him out of office this November.

Moore said in a statement on Thursday, “Senator Tester showed his true colors by refusing to personally condemn even the most unhinged, far-left fringes of his party who’ve gone so low as to call for outright violence against the President of the United States.”

The NRSC also released an ad Thursday detailing Sen. Tester’s relationship with the controversial Pearl Jam poster. Part of the transcript reads:

Now, a rock band comes to Montana, throws a concert to support Tester–and promotes it using a vulgar, despicable poster featuring President Trump’s dead corpse on the White House lawn. Yet Tester himself remained silent for days. Even worse? Tester’s campaign used the concert to raise campaign cash, charging up to $500 for VIP tickets. How much dirty money did Tester raise? And if he won’t do the right thing and give it back, doesn’t that tell us all we need to know about the real Jon Tester?:

“If Senator Tester won’t do the right thing, Montana voters should do it for him and vote him out of office,” Moore added.