“If you break our laws by entering this country without permission and give birth to a child, we reward that child with U.S. citizenship and guarantee full access to all public and social services this society provides, and that’s a lot of services,” Mr. Reid said in a 1993 Senate speech that would mesh easily with the current opposition to the newly passed Senate immigration overhaul.

Now Mr. Reid, the Nevada Democrat and majority leader, is a chief advocate of creating a path to citizenship for millions of unauthorized immigrants. Not only did he embrace the cause of Hispanics to help him win a difficult re-election race in 2010, he has shown national party leaders the advantages of a strong pro-immigration stance…

“I came to the realization that I was way off base,” Mr. Reid said of his prior stance, one he said he reversed after his wife, Landra, reminded him that she was the daughter of a Russian immigrant. “I am so glad she righted the ship.”…

With a rapidly growing Hispanic population back home, Mr. Reid had ample incentive to try to increase his appeal to that constituency and organize Hispanics politically even when others advised against it or saw it as fruitless.