The head of the Sierra Club is having some fun trolling the GOP.

The Republican National Committee reportedly can’t find enough willing speakers to fill time at its convention in Cleveland a few weeks away. Politicians like Sens. Lindsey Graham (R-S.C.) and Kelly Ayotte (R-N.H.) have refused the spotlight because they think the party’s presidential nominee, Donald Trump, is toxic.

So Michael Brune, executive director of the Sierra Club, emailed RNC chair Reince Priebus on Wednesday and generously offered to step in during the party’s time of need.

“I heard that you are having trouble finding speakers for the Republican National Convention in Cleveland,” Brune writes in his email. “Don’t worry — I’m here to help. I’d be happy to take the stage at the Republican National Convention, and discuss the future of energy policy in this country. Name a time.”

Brune suggests that he’d “be telling much of the crowd exactly what they want to hear,” as 72 percent of Republicans want to see increased use of renewable energy. “Jobs in clean energy production are being rapidly added in Georgia, Texas, and other traditionally red states.”

It’s not the first time that Brune has reached out to Republicans. In May, he penned an open letter to Charles Koch after a Koch spokesperson said he believed that humans were contributing to climate change: “I wanted to write to welcome you into the not-very-exclusive club that includes the strong majority of Americans, 99+% of scientists, nearly all Democratic candidates and a growing number of conservative Republicans, who all believe the same thing. We’re happy to have you!”

He’d be happy to welcome Republican politicians to the fold too, if they’re willing. For now, he’ll just troll them.