Democratic presidential candidate Sen. Bernie Sanders, I-Vt., appears to be losing traction to another progressive running in 2020, according to Juan Williams.
"She's been leap-frogging him," Williams said of Warren.
"I think these two nights really seal that that it's her moment. She's got that lane in terms of left-wing Democratic Party politics.
"She's rising and he's fading. We'll see what happens."
He added Rep. Eric Swalwell, D-Calif., did not look comfortable on the dais Thursday.
"When you look at someone like Swalwell, I think he looked stiff," he said.
Williams added the Democratic presidential primary field is overall very unwieldy.
"I think the field is too big," he said.
"So you get people who shouldn't be on the stage."
For his part, Sanders verbally swiped at Swalwell following Thursday's debate, after the California Democrat told former Vice President Joe Biden to "pass the torch" to a younger generation of candidates.
"I think that's kind of ageism to tell you the truth," Sanders responded.
"And I think what we're trying to do and all of us are trying to do is to end discrimination in this country against women, against minorities, against the LGBT community, and I think ageism as well."
Fox News' Joseph Wulfsohn contributed to this report.