House Majority Leader Eric Cantor is often photographed walking a few paces behind Speaker John Boehner, whose job he is believed to covet with a more-than-healthy dose of ambition. But is Cantor's aggressiveness fomenting trouble in Republican ranks?

Roll Call previously reported that Cantor's support for freshman Representative Adam Kinzinger in a primary against veteran Representative Don Manzullo "drew the ire of Manzullo and some older members of the GOP conference."

On Monday, two campaign finance watchdog groups, the Campaign Legal Center and Democracy 21, complicated the situation, filing a complaint with the Federal Election Commission over a $25,000 contribution made by Cantor to an anti-incumbent super-PAC that supported Kinzinger. Cantor is not the target of the complaint. Instead, the six-page complaint cites Representative Aaron Schock of Illinois, saying his publicly acknowledged solicitation of the $25,000 from Cantor was a blatant violation of election law.

Federal officeholders may solicit funds only "in connection with an election for a Federal office" if the funds comply with the limits set by the Federal Election Campaign Act, the complaint states. An FEC advisory opinion says the legal limit for such a solicitation is $5,000, which suggests that Schock was $20,000 over the line.

Cantor is also taking sides in the Indiana Senate primary pitting Indiana State Treasurer Richard Mourdock, a Tea Party favorite, against incumbent Senator Richard Lugar. The interesting twist in Indiana, however, is that Cantor is backing Lugar, whose brand of politics hearkens back to a kinder, gentler conservatism. A Cantor-backed group, the Young Guns Network, is accusing Mourdock of being too "extreme" because he wants to eliminate the Department of Education. That characterization will no doubt come as a surprise to many members of the House Republican Caucus -- who support similarly "extreme" action.

(Francis Wilkinson is a member of the Bloomberg View editorial board. Follow him on Twitter.)