Even if people think the President dropped the ball on immigration, I doubt that will make them vote for Democrats. The GOP at least has the philosophical capacity to reject benefits for illegal aliens while the Democrats simply have to throw open the doors and hand them money.
Could be but my fear is that many ,many frustrated Pubs will simply stay at home and not vote allowing Dems to win by default. That could really hurt even if in the Blue states there will be chances of pickups.