More election security experts have joined Jill Stein’s campaign to review the presidential vote in battleground states won by Donald Trump, as she sues Wisconsin to secure a full recount by hand of all its 3m ballots.

Half a dozen academics and other specialists on Monday submitted new testimony supporting a lawsuit from Stein against Wisconsin authorities, in which she asked a court to prevent county officials from carrying out their recounts by machine.



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Stein argued that Wisconsin’s plan to allow automatic recounting “risks tainting the recount process” because the electronic scanning equipment involved may incorrectly tally the results and could have been attacked by foreign hackers.



“There is a substantial possibility that recounting the ballots by hand will produce a more correct result and change the outcome of the election,” Stein argued in the lawsuit in Dane County circuit court. A copy was obtained by the Guardian.

Stein, the Green party’s presidential election candidate, is working to secure full recounts in the states of Michigan, Pennsylvania and Wisconsin, where Trump surprised pollsters by narrowly beating Clinton on his way to a national victory in the electoral college.

A petition from Stein requesting a recount was accepted by Wisconsin last Friday. Her efforts to obtain a recount in Pennsylvania met serious difficulties on Monday as it became clear she needed three voters in each of the state’s 9,163 voting precincts to request a recount on her behalf, and that deadlines to do so had passed in many precincts.

Wisconsin also told Stein on Monday that the recount, which was previously estimated to cost $1m, would actually cost $3.5m and that the funds must be produced by the end of Tuesday. Stein has raised more than $6m for the three-state recount effort using online crowdfunding.

The election took place amid warnings from the US government that Russian hackers had been detected in the voter registration systems of some states and were responsible for the theft of emails from the Democratic National Committee and from John Podesta, the chairman of Clinton’s presidential campaign.

Stein’s effort to have votes recounted, which she is spearheading on behalf of a loose coalition of experts and activists, has been sharply criticized by Trump and his allies, as well as people from across the political spectrum. Late on Monday, however, a new group of academics came out in her support.

Professor Poorvi Vora of George Washington University said in an affidavit that hackers could have infected vote-scanning machinery in Wisconsin with malware designed to skew automatic recounts as well as the original vote count.

“It is not possible to determine with certainty the absence of malicious software hiding within what might appear to be many thousands of lines of legitimate software code,” said Vora, who added that the only way to ensure the integrity of the count was a recount by hand.

Wisconsin officials have said the recount must be completed by 8pm on 12 December in order for the results to be finally certified by the following day in time for a federal deadline. Fearful that hand recounts would take too long, the state’s election commission has told counties they may decide how they recount their ballots, prompting the lawsuit from Stein.

Arguing that a manual count of paper ballots was the only way to ensure there had been no outside interference, Professor Ronald Rivest of the Massachusetts Institute of Technology quoted the Russian proverb made famous by president Ronald Reagan: “Trust, but verify.”

“We have learned the hard way that almost any computer system can be broken into by a sufficiently determined, skillful, and persistent adversary,” said Rivest.

Professor Dan Wallach of Rice University said it was “entirely reasonable” to suspect that a foreign adversary was capable of a sophisticated and targeted attack on the American electoral process. “They know about battleground states,” he said.

Wallach cited the US-Israeli hacking of Iran’s nuclear program to argue against skeptics who insist that voter machines cannot have been hacked because they were not connected to the internet.

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“The Stuxnet malware for example was engineered specifically to damage nuclear centrifuges in Iran even though those centrifuges were never connected to the internet,” said Wallach.

Other experts pointed to more prosaic reasons for holding a full recount by hand.

Professor Philip Stark, director of statistical computing at the University of California, Berkeley, said that Trump’s winning margin in Wisconsin of about 22,000 could “easily be less” than the errors frequently made by the optical voting systems used in most counties, which scan paper ballots marked by voters.

“To determine whether the reported winner actually won requires verifying the results as accurately as possible, which in turn requires manually examining the underlying paper records,” said Stark, who wrote a newspaper op-ed with Rivest calling for a review of the election before Stein announced her recount efforts.

The group who filed affidavits in support of Stein on Monday also included Douglas Jones, an associate professor at University of Iowa, and Harri Hursti, a Finnish expert on the hacking of electronic voter machines.