I seriously doubt that Obama would have appointed Comey, without knowing he was a cooperative kind of fellow, when it got really dirty and partisan.
I cite letting Hillary off, twice for her emails.
First time, to effectively placate his agents, by listing her offense, then claiming it was unintentional and playing prosecutor and claiming no jury would convict.
Next by reviewing some more last minute emails, and again saying there was nothing there.
After watching inept congressional committees under Issa, Gowdy and others, the dems must have thought Comey's performance would win the day.