(CNN)Hillary Clinton's campaign is being urged by a number of top computer scientists to call for a recount of vote totals in Wisconsin, Michigan and Pennsylvania, according to a source with knowledge of the request.

The computer scientists believe they have found evidence that vote totals in the three states could have been manipulated or hacked and presented their findings to top Clinton aides on a call last Thursday.

The scientists, among them J. Alex Halderman, the director of the University of Michigan Center for Computer Security and Society, told the Clinton campaign they believe there is a questionable trend of Clinton performing worse in counties that relied on electronic voting machines compared to paper ballots and optical scanners, according to the source.

The group informed John Podesta, Clinton's campaign chairman, and Marc Elias, the campaign's general counsel, that Clinton received 7% fewer votes in counties that relied on electronic voting machines, which the group said could have been hacked.