Bachmann noted in June that she did not intend to participate in a media-driven "mud wrestling fight" against Palin, while the former Alaska governor said during an appearance at the Iowa State Fair on Saturday that attempts to suggest a particularly charged rivalry between her and Bachmann were sexist and "so passé."

But the Palin camp privately became agitated when Bachmann did not rise to Palin's defense last January amid the fallout from the mass murder in Arizona and attempted assassination of Arizona Rep. Gabby Giffords; following that tragedy, Palin took heat from some liberals for using gun imagery in a 2010 campaign map that targeted Democratic officials for electoral defeat.

If Palin does enter the presidential race sometime next month, the antipathy between her campaign team and Bachmann's is likely to become more apparent, as each side competes for a similar voting bloc.