Sen. Ted Cruz (R-TX) on Monday requested information from Wikipedia regarding mounting unease that the internet’s leading online encyclopedia is manipulating narratives to promote left-wing viewpoints.

“Wikipedia began with a noble concept: crowdsource human knowledge using verifiable sources and make it free to the public,” the senator wrote in a letter to Wikimedia Foundation CEO Maryana Iskander. “That’s what makes reports of Wikipedia’s systemic bias especially troubling.”