Let's set this straight. The FBI Director James Comey did not say they was re-opening the Hillary Clinton email server investigation. But he set that false rumor in motion, and Republicans are seeing that it snowballs. Here's what we know at this point.
1. James B. Comey testified about the investigation of the Clinton email server before the House Oversight Committee last year, and he said under oath that his report on the investigation was a full and complete report. Now the FBI has come across some more emails through an "unrelated investigation" that may -- or may not -- have some bearing on that testimony. They don't know yet. But it could mean that his report to the committee is no longer full and complete. So he felt it necessary to notify the committee of that fact, even though it will require further investigation to see if it does have some bearing on the Clinton case.
2. The "unrelated investigation" turns out to be a computer seized in the FBI investigation of Anthony Weiner in his sexting with a 15 year old girl. Weiner is separated from his wife, Huma Abedin, who is a top aide to Hillary Clinton. She also used that home computer. Apparently she exchanged some emails with her husband using her cell phone, which uses the Clinton server. Hence the possible -- not proved -- connection with Clinton's case.
3. The Republican chair of that committee, Jason Chafetz, promptly tweeted out that the FBI is reopening the Clinton email server case. That is not true. This was obviously done for maximum political purposes by this partisan committee chair. And of course the Trump campaign has seized on this and making wild claims about proof that Hillary is a crook.
4. What is not known is FBI Director Comey's motivation in doing this now in a way he should have known would immediately be used for political purposes by the Republicans he sent the letter to. He is widely regarded by both Democrats and Republicans as a straight shooter, having been the Acting Attorney General who stood up to Dick Cheney and George Bush who tried to bulldoze AG Ashcroft into signing off on an illegal surveillance renewal program while he lay ill and under sedation in the hospital. President Obama appointed him to be FBI Director.
5. Despite Comey's stellar reputation, this is totally unprecedented. The FBI is traditionally extremely careful not to release information close to an election time about any investigation that might affect the outcome of an election. Serious questions were raised by Comey's public statement last year about the Clinton server investigation. And now this raises grave criticism and serious questions about his integrity in doing this -- with apparent total disregard for how it would be misused.
6. Democratic ranking member on the Senate Intelligence Committee Diane Feinstein wrote a scathing letter, criticizing Comey. The Clinton campaign has called for him to release the full information which would presumably show that no classified information was compromised by this route. They are not afraid of the truth; they're being hurt by the Republican speculations and assumptions.
7. Comey seems to be either very naive, or excessively pedantic in thinking he needed to correct his statement of "full and complete" as quickly as possible, rather than waiting 11 days -- or else he is engaging in the worst sort of partisan leaks from the highest legal office of the United States Department of Justice. I'd hate to think it is the latter. But Comey is a Republican. He sent this letter to Chafetz without even seeing the emails, and they are said by sources to be neither to or from Clinton herself.
8. It's unlikely that this will change the outcome of who wins the presidential election. But, if not cleared up in the next day or two by Comey himself, it will likely slow the momentum for a Clinton landslide, which will affect down ballot races. It could make a difference in the control of the Senate and House.
9. AG Comey, it's your move to correct this mess you have set in motion.
Late addition: Apparently Comey felt under pressure in the other direction: that if he didn't notify the committee -- which has already been accusing him of cover-up -- and this did prove to be something, then they would charge him with real cover-up. So he leaned over in the other direction and created an opportunity for partisan politics to go into play before the election and possibly change the course of the election. Bad choice. This close to an election, if you don't have incontrovertible proof of something, you should just keep quiet.