On Sunday, Lieberman called Ocasio-Cortez's reaction on Twitter "kind of silly". He retired in 2013 after serving 24 years in the U.S. Senate.
Lieberman, 76, explained that Ocasio-Cortez, 29, is too "different" and "controversial" for the party, which he says has shifted to the center of the political spectrum. Millennials often use such a response to avoid unwanted conversations through text messages by pretending they have no idea who is trying to them.
The report described lawmakers as fearful of Ocasio-Cortez's ability to swing progressives against more establishment Democrats and anxious to utilize her influence to unite the party.
"Time to walk the walk", Ocasio-Cortez wrote on Twitter.More news: Graham says Trump isn't giving in on border wall
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Responding to a news story about fellow Democrats who were hoping to rein her in, Ocasio-Cortez said, "To quote Alan Moore: 'None of you understand".
Vocal critics of the approach say it's an expensive clone of socialized medicine systems found in Canada, Scandinavia and elsewhere.
Lieberman pointed to the many moderate Democrats who beat Republicans in purple districts in 2018.
Despite Ocasio-Cortez' telegenic approach to self-promotion and her social media star power, Democratic House leaders have sought to sideline her in practical ways that could limit the public's exposure to her less mainstream views. You don't get picked for committees by who your grass-roots [supporters] are'. Ocasio-Cortez thrust that issue into the national dialogue after she joined a sit-in protest in the office of then-incoming House speaker, Rep. Nancy Pelosi, in one of her first, rebellious acts in Washington.
"She just takes us back to the big-spending, big-taxing Democratic Party, and the Democratic Party is not going to succeed that way", Lieberman told Fox News Channel's Maria Bartiromo on "Sunday Morning Futures".