In OTL the Democrats won by about 1.2% of the popular vote in 2012, but due to structural factors the Republicans ended up with a large house majority. What would the consequences be if they'd won a narrow majority of the seats (ex 220-215 split).
The biggest butterfly I would see coming from this scenario is the 2013 immigration bill, which almost certainly would have passed a democratic house (unless you assume that Republicans in the senate wouldn't have supported it if they knew it would pass).
That and there might be some more conflict over the role of movement conservatives if the 2010-12 period was seen as to blame for wiping out again.
So, thoughts?