“It’s stunning that Republicans won the white vote by 20 points and still lost,” said Alan I. Abramowitz, a political scientist at Emory University who writes about polarization. Unless Republicans reverse the trend, he said, the rising strength of Latinos could doom the party’s ability to map a winning electoral strategy. Colorado and Nevada could soon join California and New Mexico as noncompetitive states for Republicans in presidential elections, with Florida not far behind.

“And eventually Texas,” Dr. Abramowitz added. “Not 4 years or 8 years from now, but in 12 or 16 years Texas is going to become a swing state. And if Texas becomes a swing state, it’s all over.”…

But the Republicans will also have to overcome the tone set by Republican-led states that have enacted tough new measures aimed at catching illegal immigrants. Latinos will never vote Republican, said Mr. Treviño, the former Bush speechwriter, “if they think your political party just doesn’t want you as a neighbor.”