Hillary Clinton says Bernie Sanders would not be strongest nominee

"I don't think he'd be our strongest nominee, no," Clinton told ABC News in an interview aired Tuesday.

"That's what this primary process is about," Clinton continued. "Let's see who emerges, but for everybody voting today or in any of the contests ahead of time, the most important issue is who can defeat Donald Trump."

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Clinton's comments come on Super Tuesday, the biggest day of the 2020 contest. Voting is underway in 14 states and one US territory, and the critical contests will decide about one-third of all pledged delegates.

CNN has reached out to Sanders' campaign for comment.

The former secretary of state has criticized Sanders in recent months, highlighting the discord between Clinton and Sanders years after their contentious Democratic primary fight in 2016.

In a new documentary, Clinton said "nobody likes" Sanders or wants to work with him, and that he got "nothing done" in Congress. Clinton in February insinuated to talk show how Ellen DeGeneres that if Sanders' potential failure to "deliver the moon" would detract from efforts to rebuild public trust.

After initially declining in an interview with the Hollywood Reporter in January to say whether she would endorse and campaign for Sanders if he is the Democratic nominee, Clinton later clarified she would support the Democratic Party's eventual presidential nominee.

Sanders' campaign declined to comment at the time Clinton made the comments to DeGeneres. When Clinton's comments in the documentary were reported, Sanders said in a statement that his focus was on Trump.