President Donald Trump vowed to stand for free speech on Thursday, warning Big Tech against censoring conservative voices.

“I’ve made it clear that we as a country cannot tolerate political censorship, blacklisting, and rigged search results,” Trump said, calling out social media companies like Google, Facebook, and Twitter.

The president commented on the issue at his campaign rally in Indiana on Thursday night, ahead of the midterm elections in November.

Trump said his administration would always stand up for free speech for “all Americans,” warning the left that their own voices could someday be censored.

“We will not let large corporations silence conservative voices,” he said.

Trump suggested that such activities were un-American, reiterating the principle of free speech.

“We’re not going to let them control what we can and cannot see, read, and learn from, we can’t do that,” Trump said. “America is a free country and we’re going to stay always a free country.”