Democrats.
The Southwest is going to turn over to the left strongly from the Hispanic voter population growth. By 2024 Arizona and Texas will be voting Democrat in national elections.
Just look at Texas in 2008. It was McCain @ ~55% and Obama @ ~44%:
http://en.wikipedia.org/wiki/United_States_presidential_election_in_Texas,_2008Most polls for 2012 show that 11-12% gap closing to 5% or less. In fact the recent polls show Perry LOSING to Obama in Texas in 2012. Good luck keeping Texas electoral votes for Republicans after 2012.