I think the picture is more complicated than that. And that the demise of the Republican Party is no more foreordained than it was a century ago when Italian, Jewish and Polish immigrants were pouring into the United States in proportions much greater than the Hispanic and Asian immigration of the past two decades.
The numbers do appear stark. The Census tells us that 16 percent of U.S. residents are Hispanic, up from 13 percent in 2000 and 9 percent in 1990, and that 5 percent are Asian, up from 4 percent in 2000. The percentage of blacks held steady at 13. Among children, the voters of tomorrow, those percentages are higher.
But it's a mistake to see blacks, Hispanics and Asians as a single "people of color" voting bloc. The 2010 exit poll shows that the Republican percentages in the vote for the U.S. House were 60 percent among whites, 9 percent among blacks, 38 percent among Hispanics and 40 percent among Asians.
Simple arithmetic tells you that Hispanics and Asians vote more like whites than like blacks. The picture is similar in the 2008 exit poll.
Moreover, while blacks vote similarly in just about every state, there is wide variation among Hispanics. In 2010 governor elections, Hispanics voted 31 percent Republican in California, 38 percent Republican in Texas and 50 percent Republican in Florida (where Cubans are no longer a majority of Hispanics).
As RealClearPolitics senior political analyst Sean Trende has written, Hispanics tend to vote 10 percent to 15 percent less Republican than whites of similar income and education levels. An increasingly Hispanic electorate puts Republicans at a disadvantage, but not an overwhelming one.
The same is true of Asians. In 2010, Democratic Sen. Harry Reid got 79 percent from Asians in Nevada, where many are Filipinos. But the Asians in Middlesex County, N.J., most of whom are from India, seem to have voted for Republican Gov. Chris Christie in 2009.
The 2010 Census tells something else that may prove important: There's been a slowdown of immigration since the recession began in 2007 and even some reverse migration. If you look at the Census results for Hispanic immigrant entry points -- East Los Angeles and Santa Ana, Calif., the east side of Houston, the Pilsen neighborhood in Chicago -- you find that the Hispanic population has dropped sharply since 2000.