AP/Chris Tilley
Mitt Romney
"No question about that in my mind. The American people may disagree with me," Romney said in a "Fox News Sunday" interview.
He argued Clinton, President Barack Obama's former secretary of state, lacks the necessary experience run the country.
"Look, you've got to get this economy going. You've got to have people that know what it takes to create jobs," Romney continued. "You've got to have that understanding. You've also got to have people who have actually run something. ... I don't think Hillary Clinton has that experience."
Romney further said Clinton is too linked to the current White House to be able to present a record that's not a complete "disaster."
"I look for instance at her record as secretary of state. Look, her record is Barack Obama's record in foreign policy. And it's a disaster," he said. "Hillary Clinton and Barack Obama are two peas in the same pod. And the American people have tasted that and have said, 'Look, it's not a good taste.'"
Romney, the 2012 Republican nominee, has repeatedly insisted he won't mount a third campaign for the job. However, his criticism of Clinton, the expected Democratic nominee in two years, will likely only increase speculation that he is privately keeping his options open.