While Mr. Kemp insisted that these investigations were about preventing in-person voter fraud (which basically doesn’t exist), he was more candid when talking with fellow Republicans: “Democrats are working hard,” he warned in a recording released by a progressive group “registering all these minority voters that are out there and others that are sitting on the sidelines.”

“If they can do that, they can win these elections in November,” Mr. Kemp said. Therefore, even after the multiple investigations yielded no indication of fraud, thousands of people registered during these drives were not on the voter registration rolls, and a court ruling kept it that way.

Mr. Kemp also used Exact Match, a version of the infamous Crosscheck database, to put tens of thousands of citizens in electoral limbo, refusing to place them on the rolls if an errant hyphen, a stray letter or a typographical error on someone’s voter registration card didn’t match the records of the state’s driver’s license bureau or the Social Security office.

Using this method, Mr. Kemp blocked nearly 35,000 people from the voter rolls. Equally important, African-Americans, who made up a third of the registrants, accounted for almost 66 percent of the rejected applicants. And Asian-Americans and Latino voters were more than six times as likely as whites to have been stymied from registering .

But as diligent as he has been about purging eligible citizens from the voter rolls, Mr. Kemp has been just as lax about the cybersecurity of the state’s 27,000 electronic voting machines. Although there were a series of warnings about the ease with which they could be hacked, Mr. Kemp did not respond. Georgia’s electronic voting machines, which run on Windows 2000, leave no paper trail; as a result, there is no way to verify whether the counts are accurate or whether the vote has been hacked.

But the Department of Homeland Security warned him that hacking was a possibility. He ignored that until 2016, when, at a DefCon hacker convention in Las Vegas, an organization took control over the way Georgia’s voting machines register and store votes, although it had little expertise in voting matters. Mr. Kemp finally accepted federal dollars, which he had refused for years, to update some of the machines. But his efforts were too little, too late.

That complacency was evident when groups sued the state, alleging that the 2016 presidential election and a 2017 special election had been hacked. Rather than being on high alert to get to the bottom of it, after Mr. Kemp received notification of the lawsuit, officials at Kennesaw State University, which provides logistical support for the state’s election machinery, “destroyed the server that housed statewide election data.” That series of events, including an April visit to the small campus by Ambassador Sergey Kislyak of Russia, raised warning flags to many observers. But not to Mr. Kemp, who said that there was nothing untoward in any of it; the erasure was “in accordance with standard IT procedures.”