A group of researchers say there is "mixed evidence" that a late-October letter from FBI Director James Comey swung the November 2016 presidential election in favor of Donald Trump, who spent nearly all of the campaign trailing Hillary Clinton in the polls.
"We would conclude there is at best mixed evidence to suggest that the FBI announcement tipped the scales of the race," wrote a panel of polling experts at the American Association for Public Opinion Research.
"Another way to analyze a possible impact of the [Oct. 28] FBI letter is to check whether, all else equal, the trend in support changed following the release of that letter," the panel explained. "To test this, we conducted a regression analysis using all national public polls fielded between September 1st and Election Day. This analysis, which controlled for change over time and methodological characteristics of the polls, indicates that the Comey letter had an immediate, negative impact for Clinton on the order of 2 percentage points. The apparent impact did not last, as support for Clinton tended to tick up in the days just prior to the election."
On Oct. 28, 2016, approximately two weeks before the Nov. 8 election, FBI Director James Comey sent a letter to Congress saying that his agency had found new emails related to the investigation into Clinton's use of email while secretary of state.
On Nov. 6, slightly over a week later, Comey announced that the FBI had found no wrongdoing on behalf of Clinton. The election took place two days after that.
Clinton herself cited Comey's Oct. 28 letter to Congress as a deciding factor in her loss: "If the election had been on October 27, I would be your president,” she told CNN anchor Christiane Amanpour on May 3, 2017, according to the Washington Post.
During Senate testimony on May 4, Comey said he had to make a tough decision on whether to be transparent and risk affecting a presidential election or hide evidence from Congress and the public.
"This was terrible. It made me mildly nauseous to think that we might have had some impact on the election, but honestly, it wouldn't change the decision," Comey said, according to Politico. "We honestly made a decision between those two, those two choices, that even in hindsight -- and this has been one of the world's most painful experiences -- I would make the same decision. I would not conceal that, on Oct. 28, from the Congress. ... I knew there'd be a huge storm that would come."
During Clinton's tenure as secretary of state, she kept government work emails on a private server in her home. After public records requests from legal groups and reporters revealed Clinton's email situation, the FBI conducted an investigation. It eventually found no criminal wrongdoing, although Comey did refer to Clinton's actions as “extremely careless,” according to Wired.
After the original FBI investigation concluded in July, it was considered a done deal. But Comey's Oct. 28 letter renewed interest in Clinton's email scandal.