Brad Raffensperger, the Republican secretary of state in Georgia and a candidate for governor, received a “manifesto” deemed to be a “credible threat on his life” Monday, the day before a suspicious object disrupted a campaign event in Macon, campaign officials said. The four-page, handwritten document included a photograph of Raffensperger with the word “Boom” written across his forehead, campaign officials said. It was “multipage,” and “it was obviously targeting the secretary of state,” Ryan Mahoney, a campaign spokesperson, told The New York Times. Raffensperger has been the subject of hundreds of threats since the 2020 presidential election, when he bucked President Donald Trump’s efforts to reverse his defeat. The letter was mailed to the sheriff’s office in Clay County, Mississippi, which notified the FBI, officials with Raffensperger’s state office and his campaign said.…