Story highlights Julian Zelizer: FBI director's letter to Congress not the first bit of bad campaign timing

Before '92 vote, GOP blasted news of Iran-Contra memo on George H.W. Bush, he says

(CNN) Democrats are up in arms about FBI Director James Comey's letter to Congress revealing that he is looking into more emails related to Hillary Clinton. Although the contents of those emails remain a mystery and at this point no evidence indicates new material, news of the letter created an uproar in the final days of the 2016 campaign. Members of Clinton's team have spent the entire weekend scrambling to respond. They have focused on painting Comey -- whom they had praised when he ended the investigation in July -- as a rogue or partisan official undermining a fair election.

Donald Trump and most Republicans are affirming Comey, only weeks after they condemned him for letting Clinton off the hook. What's more, with Trump blitzing the airwaves with speeches about Clinton's corruption, he and the Republicans have found common ground -- previously in short supply -- in claiming that the FBI director did his job, safeguarding the integrity of his agency. Despite reports that Attorney General Loretta Lynch disagreed with his decision, Comey's supporters insist that he had no choice: If he didn't send the letter to Congress and this part of the investigation was leaked, he would be accused of a cover-up.

Julian Zelizer

This isn't the first time late-breaking news about an investigation came right toward the end of a presidential campaign. Another October surprise emerged in the 1992 race, and Republicans were the ones complaining. Their candidate, President George H.W. Bush, was implicated in an investigation into the Iran-Contra scandal when a memo surfaced on October 30, 1992.

The Iran-Contra scandal revolved around the revelation in 1986 and 1987 that members of Ronald Reagan's administration had traded arms to Iran in exchange for help with the release of hostages in Lebanon. Following the revelation of the scandal in 1986, the Department of Justice appointed an independent prosecutor, Lawrence Walsh , a registered Republican. Although Congress had failed to turn up any "smoking gun" connecting these activities to the president himself, Walsh continued with a multiyear, multimillion-dollar investigation. In June 1992 , a grand jury indicted former Defense Secretary Caspar Weinberger on five felony charges, including obstruction of justice.

Then, on October 30, the news got worse. Walsh announced that he found a memo, from January 7, 1986, in which Weinberger noted that Bush, then vice president, knew about the sales of arms to Iran. Bush had always insisted that he knew nothing of this operation. The memo suggested he was not telling the truth.

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