Is Gingirch's personal past and 'fidelity pledge' fair game? Contributor Ruben Navarrette on why a candidate's personal life should be off limits

Newt Gingrich has come under attack recently for past marital troubles. 

The thrice married, twice divorced former House Speaker was even heckled Wednesday by one Occupy Iowa City demonstrator, who told Gingrich that he had "a Ph.D. in cheating on your wife."  It remains to be seen whether these past indiscretions will affect his standing in the GOP primary race.

Today on American Morning, CNN.com contributor Ruben Navarrette tells Carol Costello that Newt's personal life should be off limits.