MASON-DIXON LINE -- En route to a Hillary Clinton rally in Harrisburg, Pennsylvania, I just heard Rush Limbaugh give marching orders to his troops in "Operation Chaos," his mischievous campaign to create confusion in the Democratic primary race. Right now, Limbaugh is pushing Republican voters in Pennsylvania to vote in the primary for Mrs. Clinton, yet Mr. Limbaugh admits, "Odds are Obama will win." However, Limbaugh, noting a large number of recent changed party registrations, predicted a large turnout of Republican voters for Hillary tomorrow. Limbaugh encouraged his "Operation Chaos" troops: "Brave volunteers, press on!...As the outcome becomes more obvious, remember the Alamo!"