Country music icon Willie Nelson debuted a surprise political anthem during a rally for Texas Rep. Beto O’Rourke, the state's Democratic Senate nominee.

Nelson, who performed at O’Rourke's rally on Saturday night in Austin, finished his headlining set with a premiere of “Vote ‘Em Out,” a rallying cry to get voters to the polls.

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"The biggest gun we got is called the ballot box,” Nelson sang. “If you don't like who's in there, vote 'em out.”

“Election Day is coming ‘round again,” Nelson sang, urging attendees to cast their ballots to vote out this "bunch of clowns you voted in." The audience enthusiastically sang along with Nelson during the performance.

Good night to everyone but especially @BetoORourke and @WillieNelson who wrote a brand new song for tonight: “The biggest gun we got/Is called the ballot box/And if you don’t like who’s in there, VOTE ‘EM OUT” pic.twitter.com/LJ1CyyWgmw — Hilary Hughes (@hilmonstah) September 30, 2018

The country rock star has made political statements before, with a Trump-inspired song “Delete and Fast-Forward” released last year.

Nelson faced backlash from many fans for headlining a rally for O’Rourke, who is running to defeat Sen. Ted Cruz Rafael (Ted) Edward CruzThe Hill's Morning Report - Sponsored by Facebook - Trump previews SCOTUS nominee as 'totally brilliant' Cruz blocks amended resolution honoring Ginsburg over language about her dying wish Trump argues full Supreme Court needed to settle potential election disputes MORE (R-Texas), but said earlier this month that he doesn’t care.

Polls have repeatedly shown a tight race between Cruz and O’Rourke in the red state, which has not elected a Democrat to the Senate in decades.