I lived through the "Red Scare," from the far right,But, I also remember that Everett Dirksen had to marshall the moderates in the Republican Party to get major social legislation passed. I remember that Ed Brooke was the first post Reconstruction Black Senator in the early 1960s, and was a Republican. I remember "None Dare Call It Treason," from the far right. Republicans were rabidly anti-Communist. But, John Kennedy was also an anti-Communist. Ben Bradlee, wrote that Kennedy was also very critical of men who did not serve in the military, during the war. He was a bit of a cold warrior, but not as extreme as Ray Cohn, who his brother Robert worked along side and had nice things to say about. Liberals, in those days would not have tolerated Bernie Sanders trying to hijack the party for his own egotistical reasons. Henry Wallace was dumped from the Democratic Tidket in 1944, because FDR was expected to die, and many party leaders felt a "progressive," would lose the presidency for us. In fact racist, Strom Thurmond, got over 30-electoral votes to the Progressive Party's Wallace's zero, in 1948.
You must not have been paying attention in 1992, because you would know that Bill Clinton was a founding member of the centrist Democratic Leadership Council, which was opposed by more liberal party members who preferred, Senators McCarthy, Psongas or Harkin.
Fast forward to 2019 and the Gallup Poll shows that conservatives hold a plurality of voters leaning toward them, with moderates coming in second and liberals third. In fact there is no far left wing party. But, there is a concerted effort to convince Democrats to move to the left. The Democratic Party is a mostly liberal party. Liberals are more like Buttigieg and Klobuchar than Sanders and Warren. While there is room in the party for people from moderates to progressives, there is a Progressive Party, and it is not us. If we want to lose in 2020, we will continue to attack average Democrats, split the party and insult moderate Republicans looking for someone to vote for next year.