Reacting to the Vox article i linked to below, Ryan Cooper outlines Obama's bad history of seeking a middle ground with Republicans at the expense of his own party's agenda and common sense.

Relatedly, Democrats are apparently fretting that the Bernie Sanders wing will apply "purity tests" to candidates in the South through groups like Our Revolution (the article reads like an open letter pleading with them). And you're goddamn right we will. For one thing, Democrats like Joe Manchin have proven that there's really no benefit in having a guy with a D next to his name if he's going to vote and make statements like a Republican all the time. So we might as well go for someone better. More importantly, we just watched a townhall with Bernie Sanders connecting with a room full of Trump voters. Bernie proves that it is possible to find common ground with Republican - voters anyway, not politicians - and you can do it without being "moderate" as centrist Dems define it (Bernie can't gut a deer, but he's the most popular politician). Whereas Obama was trying to get Republicans to agree to tax cuts in return for cutting Social Security and Medicare, Sanders had a room full of Trump voters cheering the idea of universal health care.