Many GOP leaders likely breathed a sigh of relief when the Senate immigration reform bill collapsed a couple months ago – offering political cover from proposals that threatened to shatter their party's unity. And at a time when campaigning for the presidential primary was ramping up. But while Congress has taken a hiatus from active immigration reform, GOP legislators who supported the Senate bill are still being assailed by constituents, and state-level anti-immigration legislation has been popping up across the country since the bill failed. Many observers think John McCain's advocacy of the bill is significantly responsible for his plummet...