In the 2006 and 2012 Senate races, Sanders ran as a Democrat in the primary, then refused the nomination when he won so he could run as in Independent without facing a Democratic challenger.

AOC might also want to also have it both ways, using the Democratic designation to get elected in her liberal district while bashing the party that gave her power.

…The two-party system ensures a wide range of views within a political label, and particularly within the Democratic one — exemplified by Biden and AOC’s contrasting views.

…When asked by New York magazine what her role in Congress might look like in a Biden administration, AOC groaned, followed by “Oh, God.” That is not a response one would expect to the prospective election of a member of her own party. Without betraying her beliefs, AOC could have graciously said, “I look forward to working with a Democratic president.”

…In the interview, the congresswoman who represents parts of the Bronx and Queens complained, “We’re not allowed to talk about anything wrong the Democratic Party does.” Nonetheless, she went on to complain that “Democrats can be too big of a tent” and that “they let anybody who the cat dragged in call themselves a progressive. There’s no standard.”

Perhaps AOC would be happier leaving for another party that let her set the standards.

…It’s no coincidence that the far-left Democrats — including AOC’s three colleagues in “The Squad” — were elected in very safe liberal districts. But the Democrats now control the House not because of a handful of radicals, but because 40 mostly moderate Democrats took seats from Republicans in 2018.

…Members of the [progressive] caucus often engage in the narcissism of small differences, building hostility toward Democrats holding views that diverge in minor ways.

AOC should leave the Democratic Party (opinion) – CNN

Nothing says progressive like being willing to burn the house down if they don’t get their way. It’s this kind of thinking that got us Trump.