When the Democratic Party wields power at the national level and fails to realize a stated progressive goal, mainstream Democrats invariably offer the same response to critics: we’re pushing progressive agenda as forcefully as we can, but those dastardly Republicans are in the way. As Thomas Frank puts it in his book Listen, Liberal:

When you press Democrats on their uninspiring deeds — their lousy free trade deals, for example, or their incomprehensible Wall Street reform legislation — when you press them on any of these things, they reply automatically that this is the best anyone could have done. After all, they had to deal with those awful Republicans, and those awful Republicans wouldn’t let the really good stuff through. They filibustered in the Senate. They gerrymandered in the congressional districts. And, besides, it’s hard to turn an ocean liner. Surely you don’t think the tepid-to-lukewarm things Clinton and Obama have done in Washington really represent the fiery Democratic soul.

Whatever you think of this defense, it is at least somewhat grounded in reality. America’s political system is wildly undemocratic. Its congressional map has been gerrymandered. The Republican Party does obstruct, almost by definition.