King launched political attacks against his challenger, Christie Vilsack, during a video town hall meeting with his constituents last week. The meeting was promoted heavily by King's congressional office, with mentions on his official Facebook page and in emails and tweets from congressional staff.
King's event and its promotion may violate rules that prohibit congressmen and their staff from using public resources for campaign activities.
Neither King's communications director or the Office of Congressional Ethics would comment on the matter, according to the Register.
King, who has the support of the Club for Growth, has the fundraising advantage in the race, but Vilsack's inflammatory comments and less favorable district lines may give her a chance of beating the incumbent.
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CORRECTION: An earlier version of this post misattributed the promotion of the town hall to Vilsack's office. It was promoted by King's staff.