While Ocasio-Cortez is seen by many younger, more liberal voters as the leader of a political "movement," her endorsement is not the same as if the backing was coming from other Democratic Party figures, Williams claimed Monday on "The Five."
"She is the personification of a movement for a lot of young people on the left, but I don't know that it's actually going to mean a bump in support," he said.
"I think Obama, when he endorses -- I think you could see it as 'passing the torch' to the next generation, but I'm not sure that her endorsement is necessarily a game-changer."
At a Saturday rally in New York, Ocasio-Cortez praised Sanders by claiming he is responsible for "one of the best Democratic presidential primary fields in a generation."
However, one of the Republicans vying to face-off with Ocasio-Cortez in 2020 recently ripped the lawmaker for holding the rally near what would have been the site of an Amazon complex she helped rebuff.
"They did this with 25,000 people, we heard, but omitted the fact that they killed 25,000 jobs by killing the Amazon deal right there in that part of town," Scherie Murray said on "Fox & Friends," adding that "good-paying jobs" were lost for the people of Queens and The Bronx.
On "The Five," host Greg Gutfeld noted Williams' point about the power of former President Barack Obama's endorsement, noting the Democrat recently voiced his support for a Canadian politician before his own running mate.
Gutfeld said it was "kind of sad" to see Obama endorse Canadian Prime Minister Justin Trudeau for reelection while remaining silent as former Vice President Joe Biden vies with Sanders and others for the Democratic nomination stateside.