The recent Senate debate over immigration reform focused mostly on three issues: 1) the economic effects of legalizing millions of currently illegal immigrants while also increasing the rate of future immigration, 2) the possibility of achieving real border security and 3) the ethical question of offering the reward of citizenship to those who entered the country illegally.

Beneath it all was another factor, never far from lawmakers’ minds, but much less discussed: the electoral effects of reform. Yes, there was a lot of talk about the Republican Party’s need to improve its Image with Hispanic voters. But the real political issue underlying the debate went far beyond that. Everyone knew the far-reaching Gang of Eight reform proposal passed by the Senate would reshape the American electorate. And now, a new report suggests just how extensive that reshaping could be.