Michael Barone notes the weak field of all the Republican candidates:
Generally speaking, our two parties have wanted to nominate candidates who have shown special strength among the voters who know them best. None of the nine candidates who participated in the Fox News/Google debate in Orlando has really done that. Rick Perry and Mitt Romney have won elections by margins comparable to those of John Cornyn and Paul Cellucci, competent officeholders but not on anyone’s list of presidential candidates. Ron Paul ran well ahead of his party base in 2010 against weak opposition; Michele Bachmann has not done so in three races against vigorous opponents. Newt Gingrich’s record of running ahead of party is spotty; Herman Cain’s is nonexistent.
Rick Santorum outperformed the Republican base in 1992 and 1994, but woefully underperformed it in 2006. Jon Huntsman and Gary Johnson won solid majorities for reelection against weak opposition.
None of them has performed, at least recently, as Chris Christie did when he was defeated an incumbent governor by a 48%-45% margin in New Jersey in 2009, a year after it had voted 57%-42% for Barack Obama, or Mitch Daniels, who was reelected over a former member of Congress by a 58%-40% margin in Indiana on the same day the state voted 50%-49% for Barack Obama, or Paul Ryan, who has been reelected with between 63% and 68% of the vote between 2000 and 2010 in a district which voted Democratic for president by 49%-47% in 2000, 54%-46% in 2004 and 51%-47% in 2008. These are Republicans who have shown the capacity to overperform the party’s generic base.