The “Obamacans” that Sen. Barack Obama used to joke about – Republican apostates who whispered their support for his candidacy – have morphed into a new phenomenon, or syndrome, as detractors like to call it: the Obamacons.

These are conservatives who have publicly endorsed the presumptive Democratic nominee, dissidents from the brain trust of think tanks, ex-officials and policy magazines that have fueled the Republican Party since the 1960s. Scratch the surface of this elite, and one finds a profound dismay that is far more damaging to the GOP than the usual 10 percent of registered Republicans expected to switch sides during a presidential election.

Such sentiments reflect a collapse of the “big tent” conservative coalition that Republican President Ronald Reagan forged in 1980, uniting free-market, small-government types, Christian evangelicals, cultural traditionalists and anti-communists, now called neoconservatives. The neoconservatives, whose intellectual leaders include New York Times columnist David Brooks and Weekly Standard publisher Bill Kristol, remain firmly inside the GOP and strongly back McCain, who appeals to their model of “national greatness.” So do mainstream conservative think tanks such as the Heritage Foundation, which issues regular attacks against Obama’s economic plans, and the traditionalist magazine National Review.

Could these Conservative traitors be the answer for Obama to sprint past McCain?