Excerpt - HILLSBOROUGH, N.C. -- Bill Clinton, who called himself the "comeback kid" during his first presidential run, is pulling out all the stops for Hillary Clinton's comeback. His relentless approach to battling Barack Obama -- on the trail and inside the campaign -- is becoming key to Sen. Clinton's newfound success, as she has won four of the last six primaries. She still faces long odds in her quest to overtake Sen. Obama on the road to the Democratic Party's nomination. Dubbed the "Billification" of Sen. Clinton's campaign by some insiders, Mr. Clinton has become something of a strategist-in-chief...