But Mr. Brennan’s May 23 testimony shows that it was his actions that drove the FBI probe.

The dossier was financed by a Clinton backer and written by British ex-spy Christopher Steele. He was hired by Democratic-tied Fusion GPS in Washington.

Mr. Steele’s 35 pages of memos were first circulated in late June. In mid-July Fusion passed around another memo that made the most sensational charges. “Further Indications of Extensive Conspiracy Between Trump’s Campaign and the Kremlin” was the headline.