Take a look at an Electoral College calculator. If the Republicans fail to pass comprehensive immigration reform and thereby badly alienate the Latino community, they can write off winning Nevada, Colorado, and New Mexico. In order to win the presidency, they would have to win Iowa, Ohio, Virginia, North Carolina, and Florida. And I am being generous in assuming that Florida would still be an attainable goal. If they can’t win Florida, they’d have to replace it by winning both Wisconsin and Pennsylvania. When certain conservatives talk about abandoning any Latino outreach efforts in favor of a strategy of getting a greater share of the white vote, what they are really saying is that they can win the Electoral College by winning midwestern industrial states like Iowa, Wisconsin, Ohio, and Pennsylvania, even while losing Florida and the southwest (excluding Arizona).
One thing to consider is that this kind of strategy consigns any Republican nominee to a situation in which they have to run the table on a half dozen competitive state races in order to win the barest of majorities. If they lose even one race, they will lose. And, if they win, they will win by the skin of their teeth with almost half of the country opposed to them.
I’d add that any strategy that depends on winning Pennsylvania and Wisconsin is pretty close to hopeless. Pennsylvania was last won by a Republican in 1988 and Wisconsin was last won by a Republican in 1984. Even Iowa is problematic. Bush won it in 2004, but that is the only time since 1984 that Republicans have carried the state.
However, it doesn’t seem like the Republican House majority is thinking at all about presidential elections as they consider what to do about immigration reform. This places the Democrats in the catbird’s seat. The Democrats will be almost assured of winning the presidency in 2016 if the House refuses to pass a comprehensive bill. Yet, their chances won’t really be dimmed if the House agrees to reform. That’s because, as it stands, the Republicans have only the narrowest of chances of winning the Electoral College regardless of what they do.
Still to have a fighting chance, they need to keep as many states in play as possible, and the only way to do that is to pass immigration reform.