20 minutes ago WASHINGTON — Barack Obama became the first black presidential nominee in U.S. history on Tuesday, declaring victory over Hillary Clinton and lifting the curtain on an epic struggle for the White House against Republican John McCain. Clinton, credited by Obama as an inspiration to millions, refused to concede defeat and sparked a buzz early in the day about the possibility of a dream team by saying she's open to joining the ticket as his running mate. "Tonight, we mark the end of one historic journey with the beginning of another," Obama told nearly 20,000 cheering supporters in...