Arizona margin relative to national margin
1960: R+11.32
1964: R+23.57
1968: R+19.06
1972: R+8.11
1976: R+18.63
1980: R+22.62
1984: R+15.66
1988: R+13.48
1992: R+7.51
1996: R+6.30
2000: R+6.80
2004: R+7.99
2008: R+15.74
2012: R+12.90
Arizona population, % non-hispanic white:
1960 - 1.3m, (no data but probably within 74-77%)
1970 - 1.8m, 74%
1980 - 2.7m, 75%
1990 - 3.7m, 72%
2000 - 5.1m, 64%
2010 - 6.4m, 58%
2020? - 7.2m, 52%
I don't see how Arizona stays so Republican in the future. It's very likely going to have a relative shift like we've seen in other southwest states (CA, NV, CO, NM).
What happened in the other states is that Republican pols got increasingly strident as their margins of victory shrank. Hispanics abandon the GOP, and the GOP victories of recent years become losses. Arizona is next. Texas is at least a couple of decades away.
The white non-Hispanic voters have never been as hostile to Hispanics as they have been to blacks at the same time and place.
Obama would've come very close to carrying Arizona in 2008 if McCain wasn't the nominee.
On the average the Favorite Son effect for a Presidential election is about 10% for someone seen well in his own state. Just look at the difference between the Dole win of Texas in 1996 and the Bush win of Texas in 2000 -- and the difference between the Bush win of Texas in 2004 and the McCain win of Texas in 2008. Look also at how comparatively well McGovern did in South Dakota in 1972. The home-state advantage is all that kept Walter Mondale from losing
fifty states in 1984.
The 7.75% gain against PVI in Arizona for McCain was unusually low, but not out of range.
...I can see Arizona shifting D. Just look at how "R" Vermont used to be and how "D" West Virginia used to be. Arizona has obvious similarities in demography to California, New Mexico, Colorado, and Nevada. "More Mormons" will not be enough to stop the trend.