The Washington Post reports on the way immigration has affected the Republican primary campaign:

"This is the most volatile issue I have measured since busing in 1972," said Peter D. Hart, a Democratic pollster. "It's not like abortion or gay rights, which may touch some people or offend the moral values of some. This is something that affects everyone."

Hart compared the issue of immigration to the treaty returning to Panama the Panama Canal, which drew a visceral response in conservative circles and turned President Gerald R. Ford's GOP nomination campaign in 1976 from a cakewalk to a dogfight.

"It's been like boiling water," said Al Cardenas, a former Florida Republican Party chairman and a co-chairman of Romney's campaign in the state. "It's an issue that was in the back of Americans' minds that needed to get fixed. It wasn't a priority until numbers got out of hand. Then Congress took it up, put it on the front burner, and when nothing got done, the voters turned exasperated. Can we live with such a significant breaking of the rule of law and not be morally outraged?"