I think the Dubai brouhaha helped bring this issue to the front, even if it was a bank shot. Port security led to border security. I guess the DEMs see a chance to score a similar victory.
The dems made this 30 year old problem a major issue to divide the base. They did it through fueling these protests with the massive turnouts. They knew it would anger the base and knew there were not the votes in Congress to fix the problem and appease the angry base. Its the port deal all over with and the rats are loving it.