The Dems lost the house of representatives in Obama's years 3 and 4. Again in years 5 and 6. And then lost both the house of representatives and the Senate in Obama's years 7 and 8.
And you're wondering why they didn't make a big move left after? They lost control in 3 out of 4 elections under Obama. There is more than just the presidential election you know. The left voters never showed up after the first election.
(And imo Hilary did make a move left in climate change with the map room. And guess what, the left voters didn't show up.)