Hispanics were 9 percent of the electorate in 2008 and 8 percent in 2010. Those percentages will rise as young Hispanics come of voting age — but probably not to the levels suggested by straight-line extrapolations from the years of heavy Hispanic immigration from 1982 to 2007.
Since then, more people have migrated to Mexico from the United States rather than the other way around. The most recent immigration figures show more Asian than Latin immigrants.
Recent polls suggest that Obama may run even stronger among Hispanics than his 67 to 31 percent margin in 2008. That will help him in target states Colorado and Nevada. But polls in the biggest target state, Florida, show Hispanics about evenly divided, even though less than half are Cuban-Americans.
Republicans got 38 percent of Hispanic votes in 2010, enough to win the total national vote. In the future, Hispanics are likely to vote more Democratic than average, but not hugely so. And they're likely to become 12 to 15 percent of the electorate someday, not 20 or 25 percent.
The third group of non-whites are Asians, 2 percent of the electorate in 2008 and 2010. They're the least Democratic non-white group, 62 percent for Obama in 2008 and 58 percent for House Democrats in 2010. Current polling suggests similar numbers this year.
But Asians aren't a single cohesive group and may not be reliably Democratic over time. They voted Republican for president in the 1990s.
Most Asian-Americans live in heavily Democratic California and Obama's birth state Hawaii. In target states, they formed 3 percent of the electorate in Nevada and Virginia in 2008.
Nevada Filipinos will vote heavily Democratic. But Republicans are working the Korean, Vietnamese and Chinese communities in Northern Virginia. In non-target state New Jersey, South Asians in Middlesex County cast decisive margins for Republican Chris Christie in 2009.
So puncture a couple of myths. Romney can win even if 80 percent of non-whites vote again for Obama. And rising percentages of non-whites in future electorates will pose challenges, but not threaten doom, for the Republican Party.