Republican primary voters should rally around the GOP field's most accomplished supply-sider, the all-but-announced Rudolph W. Giuliani. Having sliced taxes and slashed Gotham's government, New York's former mayor is the leading fiscal conservative among 2008's GOP presidential contenders. Before Giuliani's January 1, 1994 inauguration, New York's economy was on a stretcher. Amid soaring unemployment, 235 jobs vanished daily. Financier Felix Rohatyn complained: "Virtually all human activities are taxed to the hilt." Punitive taxes helped fuel a $2.3 billion deficit. Mayor-elect Giuliani sounded Reaganesque when he announced he would "reduce the size and cost of city government" to balance the budget....