Massachusetts Attorney General Martha Coakley has defeated three other candidates to win the Democratic nomination in the race to succeed the late Sen. Edward Kennedy. The 56-year-old Coakley is vying to be the first woman elected to the U.S. Senate from Massachusetts. She defeated Rep. Michael Capuano, City Year co-founder Alan Khazei and Boston Celtics co-owner Stephen Pagliuca. She'll face Republican State Sen. Scott Brown in a general election Jan. 19. (More Martha Coakley stories.)