A poll released last week about the approval ratings of AZ GOP senators Kyl and McCain; both their approval ratings fell from March to August (some think as a result of their vocal support of the "grand bargain"):

McCain’s favorable rating among voters fell from 49 percent in March to 42 percent in July. At the same time, his negative rating increased from 18 percent to 30 percent.

[...]

Meanwhile, Kyl’s favorable rating fell from 46 percent in March to 40 percent in July. His negative ratings increased from 12 percent to 18 percent.

It's also interesting to note that, before the battle over immigration "reform" heated up the public airwaves in May of 2006, Sen. McCain's approval rating was at 62%; since then, it's lingered at 50% or less (according to this poll). Kyl's approval rating was at 42% in January of 2006, and, after he led opposition to the "comprehensive reform" of 2006 and ran for re-election opposing such measures, his approval rating increased to 49%. However, since his support of the "grand bargain," it seems as though his approval rating has drifted down. At least according to this poll...