Carter Page, who long before the Trump campaign helped the FBI after he was approached by actual Russian spies in the course of his work. He became an FBI asset and helped them bust those Russians. Most likely the FBI asked him to approach the Trump campaign and then report to them. The FBI based the FISA court case on Pages history with the Russians (not mentioning that he was an FBI asset) and the fictional dossier. This is felony on top of felony.