She's saying goodbye, for now at least: Rep. Michele Bachmann, R-Minn., has announced she won't seek re-election in 2014. (File photo from Jan. 4, 2012, when she left the Republican presidential race.) Jim Young /Reuters /Landov hide caption

itoggle caption Jim Young /Reuters /Landov

Hillary Clinton's "inevitability" became less certain after a debate in Philadelphia at Drexel University in October 2007. William Thomas Cain/Getty Images hide caption

itoggle caption William Thomas Cain/Getty Images

Left to right: Former Sen. Rick Santorum; Rep. Michele Bachmann; former House Speaker Newt Gingrich; former Massachusetts Gov. Mitt Romney; Rep. Ron Paul; former Minnesota Gov. Tim Pawlenty; entrepreneur Herman Cain. Emmanuel Dunand /AFP/Getty Images hide caption

itoggle caption Emmanuel Dunand /AFP/Getty Images