Sheriff Joe Arpaio

After months of fighting to avoid being interviewed, Sheriff Joe Arpaio must give a deposition under oath in the case of a Chandler officer whose police dog died last August after being left in a patrol car for more than 12 hours.

In poll after poll, illegal immigration comes in as No. 1 on the list of issues concerning Arizonans. It's a subject that resonates across demographic lines: Republican or Democrat, male or female, urban or ex-urban. Even Hispanic voters will list this as a major concern. The term "wedge issue" seems almost invented for illegal immigration but probably not in the way the GOP has envisioned. This defining issue is now driving some of the most important fractures in the Republican Party's base and its impact is likely to be felt far beyond this year's presidential contest.

Although it was spectacularly ineffective in the 2006 cycle, many Republican politicians still see illegal immigration as a vehicle for advancement. Congress has its grandstanders like retiring U.S. Rep. Tom Tancredo of Colorado but Arizona locals have been sure to get in on the action. For instance, Maricopa County Sheriff Joe Arpaio has targeted Hispanic communities with sweeps designed to nab illegal immigrants but which also routinely net brown-skinned American citizens.

Click more to view video of Sheriff Joe lamenting the "dirty politics" that took away his illegal sweeps funding.