With a demographic landscape that's well-suited to both Hillary Rodham Clinton and Barack Obama, Indiana is shaping up to be the most consequential battleground of the remaining states. In a signal of the state's importance -- and of his desire to end the evening in a place more favorably inclined to him -- Obama appeared with Hoosier-born rocker John Mellencamp on Tuesday night in Evansville, Ind., as the Pennsylvania vote was being counted. He campaigned in New Albany, just across the Ohio River from Louisville, Kentucky, on Wednesday. Clinton held a rally in Indianapolis Wednesday and was scheduled to spend...