Of course they'd rather lose than nominate someone with any progressive views. This was proven way back in 1994 when Congress went to the Republicans for the first time in decades. Every single incumbent Democrat that actually ran as an "open" Liberal was reelected that year. As Harry Truman said, "When given the choice between a Republican and a Republican, people will always choose the real Republican.
When the Wisconsin Capitol was completely occupied by the people and their labor movement, firefighters, who were bribed with the opportunity to keep their union and their contract (as opposed to the teachers), came to the Capitol to stand with their brothers and sisters, saying "We came to put our the fire workers are fighting here", Obama (who had claimed that when it came to supporting workers," I'll put on my marching shoes" ignored it all and flew off to a California fundraiser. When it came time to support a recall, the state Democrat Party put up a dumb establishment guy who had already lost (twice) to the governor.
We should also remember it was the Koch brothers who put Bill Clinton in the White House - they're the ones who funded the Democratic Leadership Council and hired him to head it. Since then the Democrats have learned to love the power, the corruption and the money. Think Scrooge McDuck swimming around in his money bin - (the Congress of the United States). What exactly would pull them back - their conscience? their values? their love for the people? - they have none of these.
So screw them. And screw Hillary and the ass (Bill) she rode in on.