As Mitt Romney tries to win over Republican voters, he's going after Newt Gingrich by questioning his conservative credentials. In an interview with the Washington Post, the former Massachusetts Governor said "He has been an extraordinarily unreliable leader in the conservative world - not 16 or 17 years ago but in the last 2 to 3 years...And even during the campaign, the number of times he has moved from one spot to another has been remarkable. I think he's shown a level of unreliability as a conservative leader today." However, Newt Gingrich says he will stick to a positive campaign. The former house speaker let go of an Iowa staffer who referred to Mormonism as a cult before joining the Gingrich campaign. .