The Obama administration's special Mideast envoy, former Senator George Mitchell, has resigned after two years spent trying to get Israel and Palestinians to enter peace talks. Sources say Mitchell, who brokered the Northern Ireland peace accord, is stepping down for personal reasons. The 77 year old has spent much of his tenure trying to restart the moribund peace process, a job that has lately become even more complicated as Hamas and Fatah have agreed to share power and the recent upheaval in the region. Mitchell served as Maine's Democratic senator from 1980 to 1995. From 2000 to 2001, he led a committee on Mideast violence that called on Israel to freeze settlements and Palestinians to prevent militants from firing on Israeli towns—issues that continue to be sticking points today.