Many are saying he's damned if he does, damned if he doesn't, and that's true. But which is worse: an active impact on an election or a passive impact on an election?

If he withholds this till after the election, he is indirectly influencing it by withhold information, which ultimately is the better route since it is still entirely speculative at this point because they still haven't even accessed the emails. Comey even said the FBI doesn't usually inform Congress about ongoing investigations. In this scenario, Trump would continue course and lose the election and when Comey reveals the renewed investigation, Republicans would be up in arms. Comey will take the punches, but at least he would have been following tradition and protocol.

On the other hand, and the current situation, he is directly influencing the election by letting this still-preliminary investigative information out. It allows people to jump to conclusions because there is so little information out there. Imagine the outrageous situation that this sinks Clinton's campaign, Trump wins because of it, and then nothing comes from the emails. It's completely irresponsible to influence public perception when the matter is still entirely speculative. Comey says he did not want to "create a misleading impression." That's exactly what he did.