The Democratic Party merely moved with the electorate. Sure, it would have been great if they had stuck to all that pro-labor policy, but I don't know if you've noticed that that kind of thing hasn't gotten votes since Reagan, and it's still not clear it's going to get votes now, especially when the chunk of the electorate you might think would respond to pro-labor rhetoric is vastly more swayed by anti-"other" rhetoric peddled by the now-populist GOP.
The problem is the electorate, and the electoral system. The politicians are merely a result.
For example, if POTUS was elected simply on a nationwide tallied vote (no EC), maybe Sanders has a chance vs. Trump in 2016 if he can drive huge progressive and young voter turnout in solid blue cities in solid blue states where that kind of thing matters not an iota with the Electoral College.
