And why do you think AZ 8 leans to the Dems? There are more Republicans in the district, and if the right person wins the primary (Graf), with people so concerned about the border, he'll get a lot of crossover votes.
The Dems in the district offer no solutions.
In 2000 GWB took 49.7% of the vote, and in 2004 GWB took 52.9% of the vote. So, to begin with, with the current political landscape, it's very unlikely that the GOP will match even GWB's 2000 numbers in an open seat, and his 2000 number in AZ-08 was less than 50%.
Otherwise, the likely Democrat nominee Gabrielle Giffords has raised $570,230; the highest Republican fundraiser is Steve Huffman at $239,659 and he's actually the underdog. Randy Graf is considered the leading GOP contender and he's raised $130,812. It is very unlikely that a Pubby is gonna beat a Dem in the AZ-08 district in this year's political landscape while outspent 2 to 1, much less when outspent nearly 5 to 1.
And the outgoing GOP congressman does not support the more likely GOP nominee, but rather says that he's too conservative for the district. And whatever the case may be, whichever Republican ends up winning the nomination will likely end up with much less cash on hand than Giffords, who will have a much easier nomination battle.