Former FBI Director James Comey tweeted on Sunday that while he mentions two presidents in his book who "help illustrate the values at the heart of ethical leadership," he includes another presidential example "as a counterpoint."

The context: Comey's subtweet is the latest salvo in a Twitter battle between President Trump and the former FBI director. Trump took to Twitter earlier this morning to unleash on Comey, calling him, a "slimeball," "not smart!" and the "WORST FBI Director in history, by far!"