Teresa Heinz Kerry is openly sceptical about George Bush's victory some four months after the election, questioning the legitimacy of the optical scanners used in some states to record votes.
"Two brothers own 80 per cent of the machines used in the United States," she said during a fund raising event in Seattle.
They are "hard-right" Republicans, she claimed, arguing that it was "very easy to hack into the mother machines".
Heinz Kerry urged Democrats to push for accountability and transparency, according to the Seattle Post-Intelligencer.
"We in the United States are not a banana republic," she said. "I fear for 2006. I don't trust it the way it is right now," she added, referring to mid-term elections.