When presumptive Republican presidential nominee Mitt Romney appears before Latino small-business owners in Washington on Wednesday, he'll address a group whose explosive birth rates foreshadow a seismic political shift in GOP strongholds in the Deep South and Southwest.

"The Republicans' problem is their voters are white, aging and dying off," said David Bositis, a senior research associate at the Joint Center for Political and Economic Studies, who studies minority political engagement.

"There will come a time when they suffer catastrophic losses with the realization of the population changes."

Over the next several generations, the wave of minority voters -- who, according to U.S. Census figures released this week, now represent more than half of the nation's population born in the past year -- will become more of a power base in places like Alabama, Mississippi and Georgia. That hold will extend across the Southwest all the way to California, experts say.

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