The campaign of Brad Raffensperger, a Republican candidate for Georgia governor, received a four-page, handwritten "manifesto" that included a photo of him with the word "boom" scrawled over his face. 

The document was mailed Monday to a sheriff's office in Mississippi and came one day before a suspicious object was discovered at a Macon campaign event, AJC Politics reported. The event was disrupted when a K-9 alerted deputies to an object inside a vending machine at the Middle Georgia Regional Airport. The object was determined not to be hazardous. 

The event proceeded with Raffensperger speaking in the airport's parking lot, which was part of a six-stop campaign. Security has been stepped up at all the campaign stops. 

Raffensperger, Georgia's secretary of state, has been the target of a backlash from President Donald Trump's supporters after he refused Trump's demand to overturn Georgia's 2020 election results. 

“When you stand on principle, when you do the right thing, when you put people ahead of politics, not everyone will like it. In fact, some people may try to intimidate you or do you harm,” Raffensperger said at the Macon event. 

Raffensperger is one of eight GOP candidates in Georgia's primary, which is on May 15.