The reason people didn't vote for these two had little to do with being "center-right". Both of them were very unpopular before they were forced as candidate undemocratically. Democrats would have won with Bernie and their chances in 2024 would have been a lot better if they did a primary to pick a candidate people actually like and want to vote for. Using an candidate people hate will work if the party is far ahead in the poll, not when it's 50/50.