Democrats have control of the White House and both branches of Congress, but progressive voters still aren't seeing much of what they want policy wise put into action. Why is that?
Part of it is the inertia of Washington, but another part is that the political parties just don't have to fight over liberal voters the way they do moderates and conservatives.
Take our last national poll as an example- 82% of liberals are Democrats, 11% are independents, and 7% are Republicans. Not a lot of variety there.
Moderates are a lot more split. 50% are Democrats, 28% are independents, and 22% are Republicans.
Conservatives are more one sided than moderates, but a lot less so than liberals. 63% are Republicans, 22% are independents, and 15% are Democrats.
Looking at these numbers, you can see why Democratic leaders sometimes seem willing to take liberal voters for granted while trying harder to curry favor with moderates and conservatives. With no viable alternative to the Democrats for liberal voters in the current political system, party leaders can play to the middle or right without much risk.