Hillary Clinton says she won't rule out questioning the legitimacy of the 2016 election if Russian meddling is deeper than previously thought.

"No, I wouldn't rule it out," the former Democratic presidential nominee told NPR in an interview published Monday.

Clinton added that she doesn't believe there are means to officially challenge the legitimacy of the presidential election.

"I don't know if there's any legal constitutional way to do that. I think you can raise questions," she said.

Clinton, who has repeatedly cast blame on Moscow for her loss, said last week the investigation into whether President Trump and his campaign colluded with Russia during the election could be bigger than the Watergate scandal.

U.S. intelligence agencies believe Russia was behind the hack of Clinton campaign chairman John Podesta's email and the Democratic National Committee, though Russian President Vladimir Putin has repeatedly denied any involvement.

"[Trump] knew they were trying to do whatever they could to discredit me with emails, so there's obviously a trail there, but I don't know that in our system we have any means of doing that," Clinton said of potentially challenging election results. "There's no doubt they influenced the election: We now know more about how they did that."