John Kerry lost in 2004 as a centrist.
Obama won in 2008 posturing as a progressive. (But then lost both houses of Congress after being exposed as a centrist)
Running as a centrist in 2016 wasn’t good enough to beat the worst most flawed candidate the Republican’s have ever put forth.
In November of 2018 Heidi Heitkamp lost her reelection bid because instead of riding the progressive blue wave she went to the center.
Claire McCaskill lost in 2018 too because she went to the center.
Joe Donnelly lost because he was a moderate or conservative Democrat, a centrist.
Bill Nelson considered a centrist and a moderate Democrat was narrowly defeated in the general election by then-Governor Rick Scott because his centrist position was not distinct enough to defeat a vulnerable Rick Scott..
The Democrats need to begin abandoning centrism.