Absolutely not. Type “Lamont Lieberman” (without the quotes) into a search engine for more info. Also “Clinton puma”. In the opposite direction, Kamala Harris lost a lot of Biden voters. Biden was considered relatively left of center (though nowhere near as leftist as Sanders) back in the day.
Left of the US Senate center, or maybe the Senate Democrat center. Not the whole US. And I mean in the 1980s, not now. Even today though, I’d consider him leftward of Kamala Harris.