When Barack Obama appeared on Wednesday at a town hall-style event at the Orange County Fairgrounds in Southern California, he was challenging the Republicans in their historic heartland. The area had been ground zero for the Goldwater revolution in the early 1960s. Orange County provided the core supporters and the money that launched Ronald Reagan’s political career in the mid-sixties. Reagan won 75 per cent of Orange County’s vote in 1984; George W. Bush won 60 per cent in 2004. The county has always been solidly Republican.

Until Obama.

The hardest of hard-core Republican congressional districts in California is coastal Orange County, centered on the wealthy town of Newport Beach – previously Chris Cox’s district before George Bush elevated him to head the SEC. California political experts were stunned on Nov. 4 when Obama carried the district – by 2,500 votes. And in the city of Costa Mesa, Obama beat McCain 51-45.

Coastal Orange County wasn’t the only Republican district Obama carried in California. As Harold Meyerson pointed out recently in an L.A. Times op-ed, California has 19 congressional districts that are currently Republican, and Obama won an astounding eight of them. (He also carried all 34 Democratic districts.)

Seven of the eight Republican districts Obama carried were in Southern California – in the distant L.A. suburbs including Palmdale, Lancaster, Simi Valley, Riverside, and also northern San Diego County.

What’s going on here isn’t a shift of traditional Republicans to the Democratic column. Older white voters still supported McCain. It’s the younger people and the Latinos in the OC who voted for Obama. Significantly, these Orange County groups are growing in numbers, while the old white Republicans are dying out.

The demographic and political shift appeared first in northern Orange County in the late 1990s, when Bob Dornan was defeated by Loretta Sanchez in 1996.

Today the Bush legacy is a problem even for Orange County Republicans. "Obama is coming to a place that could be called the scene of the mortgage meltdown crime," the normally Republican Orange County Register declared Tuesday. "The largest concentration of sub prime lenders was headquartered in Orange County when the meltdown began."

California Democrats’ immediate goal is to break the Republican stranglehold on the state legislature, where the Democrats hold a majority but where GOP assembly members blocked a centrist budget for months.

Obama knows the potential of Latino and younger voters in the OC and is obviously eager to recruit them to a permanent Democratic coalition. His visit to Costa Mesa Wednesday was one more step in achieving that goal – and by all measures a successful one.