When Willie Nelson headlined a rally for Democratic Texas Senate candidate Beto O’Rourke last month in Austin, he debuted the new political anthem “Vote ‘Em Out.” A bouncy, uniquely Nelson singalong, the song encourages Americans to exercise their right to vote on Election Day.

On Thursday, the Country Music Hall of Fame member released an official studio version of “Vote ‘Em Out,” which he co-wrote with his frequent collaborator, producer Buddy Cannon. Nelson’s sons Lukas and Micah provide harmonies on the “vote ’em out” refrain.

The “On the Road Again” singer was criticized by some conservative fans who objected to his performing at the O’Rourke rally. Unfazed, Nelson appeared on the talk show The View and defended his support for the Democrat. “Everybody has an opinion,” he said. “Everybody has a right to an opinion. I think I have one too.”

Along with his endorsement of O’Rourke, Nelson has also been an outspoken advocate for immigrants. In a release announcing “Vote ‘Em Out,” he encourages people to support the RAICES organization, a nonprofit that provides free and low-cost legal services to immigrants in his home state of Texas.

In June, at the height of the immigrant family-separation controversy, Nelson released his own statement criticizing the Trump Administration’s policy. “What’s going on at our southern border is outrageous. Christians everywhere should be up in arms. What happened to ‘Bring us your tired and weak and we will make them strong?’ This is still the promise land,” he said.