Seven former Democratic National Committee chairs who support Hillary Clinton’s presidential bid, and the family of one who is deceased, released a letter Friday arguing that she is the candidate best-equipped to beat John McCain in November. The letter was signed by former party leaders Kenneth Curtis, Charles Manatt, Debra DeLee, Don Fowler, Steve Grossman, Pennsylvania Governor Edward Rendell, and Clinton adviser Terry McAuliffe. It was also signed by the family of the late Ron Brown, who served in the Clinton administration. They write that “if the election were held today, Hillary would beat Senator McCain, but Senator Obama would...