The end could be near. Or the endgame, at least, of a surprisingly drawn-out Democratic presidential contest. Four months and 42 states after the opening Iowa caucuses, the primary in North Carolina on May 6 now looms as a pivotal final showdown between Illinois Sen. Barack Obama and New York Sen. Hillary Rodham Clinton.Obama starts with a double-digit lead in polls here, a state where 2,400 free tickets to his rally at the War Memorial Auditorium in Greensboro last week were gone within three hours of the announcement he would appear. But Clinton has appeal in the Tar Heel State, too, and is competing hard. The day after Obama's rally, she drew 1,000 supporters to the gym at Terry Sanford High School in Fayetteville for a town hall meeting."I really believe May 6 has the potential to be everything," says Joe Trippi, a strategist for the presidential bids of former North Carolina senator John Edwards this year and Howard Dean in 2004. "Every day you see increased pressure on Hillary Clinton about why she's staying in, and if she could win in North Carolina it would shut down that kind of talk and open up the possibility she could get there" to the nomination."But if he wins in North Carolina," Trippi says of Obama, "I think you're going to see things close up very quickly. You'll see a lot of superdelegates line up behind him."