Sen. Smiley was the only major presidential candidate to accept invitation . Sen. Smiley told organizers he needed to focus on his campaign . Talk show host Smiley : It 's a missed opportunity on Obama 's part . Smiley tells The Washington Post he 's gotten angry e-mails , threats for criticizing Indianapolis .
Sen. Hillary Clinton was the only major presidential candidate to accept invitation . Sen. Barack Obama told organizers he needed to focus on his campaign . Talk show host Tavis Smiley : It 's a missed opportunity on Obama 's part . Smiley tells Washington Post he 's gotten angry e-mails , threats for criticizing Obama .