Hackers set the tone for the final 100 days of the election, starting with the pilfered emails of the Democratic National Committee that were released by Wikileaks in late July. The leak established a precedent for reporting on stolen digital information in the election. U.S. officials fingered Russia as the likely backer behind the hacks. Up to 20 percent of Americans ... cast votes on digital systems without a paper trail during this election. There are enough weak spots peppered around the country to distill doubt if multiple incidents occur, said James Scott, senior fellow at the Institute for Critical Infrastructure Technology. "With the kind of stealth and sophistication that's already out there, why wouldn't a nation-state, cyber-criminal gang or activist group go into election systems that are completely vulnerable?" Scott said. The biggest cyber breaches to influence Tuesday's events may have occurred months ago and involved voter registration data. While identity theft is a concern ... the primary way hackers might exploit these stolen records is via a misinformation campaign ... Scott said, citing a Colombian hacker who used such tactics to manipulate elections in nine countries across Latin America. An unnamed Department of Homeland Security official told Politico in late September that at least 20 state elections systems had been probed by hackers. If a fraction of the electronic votes filed at Tuesday's polls or during early voting come into question, then it opens the door for challenges by political candidates.