U.S. Sen. Bernie Sanders won’t endorse former Gov. John Hickenlooper or any other candidate for the U.S. Senate seat held by Colorado Republican Cory Gardner, Sanders told a Colorado media outlet Friday.

Sanders spoke with The Denver Post before his planned campaign stop Monday at Denver’s Civic Center.

“I will do whatever I can to make sure that a Democrat beats Senator Gardner,” Sanders told The Post. “I’m going to sit out the primary and let the candidates explain their views to Colorado and hope the best candidate wins. That’s a decision for the people of Colorado, not me.”

Hickenlooper has criticized core views of Sanders’ campaign, notably Democratic socialism and Medicare for all.

“If we want to beat Donald Trump and achieve big progressive goals, socialism is not the answer,” Hickenlooper told a crowd in California in June, eliciting boos and cries of support for Sanders.

Sanders reiterated his support for these views Friday and touted his climate goal of reaching 100% renewable energy for electricity and transportation by 2030.

“In Colorado, I know there is great concern about climate change and the environment,” he said.