Under Comey, the FBI had already concluded an investigation into Clinton's use of a private email server for official communication while she was secretary of state. While Comey found her actions to be "extremely careless", she wasn't charged with a crime as she didn't act with "criminal intent".
But on 28 October 2016, Comey notified congress that the FBI were looking into new emails, possibly lending greater power to Trump's 'Crooked Hillary' nickname for Clinton. The scandal dominated headlines and drew the ire of Democrats and Republicans alike, as it was revealed that Comey had begun drafting a letter of exoneration for Clinton before the investigation was complete.
Ultimately, the FBI's second probe into Clinton didn't alter the conclusion of the first one. A Department of Justice report found no evidence of political bias in the FBI's investigation, but Comey did admit in his 2018 book A Higher Loyalty that the upcoming election may have influenced his decision to re-open the investigation.
It's impossible to say for certain whether Clinton would currently be running for re-election if it weren't for Comey, but his demand that the US elect "more women" was a little ironic, to say the least.
— Elle Chestnut 🧣☃️🧤 (@Elle Chestnut 🧣☃️🧤)
Comey's tweet celebrates the 19th amendment to the US constitution which guaranteed women the right to vote in 1920. He also appeared to lend support to Democrat vice president nominee Kamala Harris and to the multiple women running for governor of Virginia in 2021.
Given that the US ranks 75th in the world for female representation in government, they probably should elect "more women". But perhaps Comey, of all people, is not the right person to tell us that.