** FILE ** Sen. Scott Brown, Massachusetts Republican, left, shakes hands with his Democratic challenger Elizabeth Warren, right, on the set before their first debate as moderator Jon Keller, center, looks on, Thursday, Sept. 20, 2012, in Boston. (AP Photo/Michael Dwyer)

Photo by: Michael Dwyer

** FILE ** Sen. Scott Brown, Massachusetts Republican, left, shakes hands with his Democratic challenger Elizabeth Warren, right, on the set before their first debate as moderator Jon Keller, center, looks on, Thursday, Sept. 20, 2012, in Boston. (AP Photo/Michael Dwyer)