12:56 p.m. -- Mitt Romney has conceded the presidential race to President Obama.
"i have just called President Obama to congratulate him on his victory,": Romney tells supporters in Boston.
Romney also thanks wife Ann, saying "she would have been a wonderful first lady."
"I believe in America," Romney seeks a bipartisan tone. In
congratulating Obama, Romney says he will "pray for him, and pray for
this great nation."