Common Cause and Citizens for Responsibility asked for an independent investigator to explore accusations the powerful conservative majority leader and Texas Republican has provided political favors in exchange for campaign donations.
Independent counsels were appointed to conduct the ethics investigations involving past leading House members, including House Speakers Newt Gingrich, R-Ga., and Jim Wright, D-Texas, who both left office as a result of those probes.
DeLay opposes the move, going so far as to send two aides to the group's press conference Thursday to distribute materials showing donations made by the two groups to Democrats.
Outgoing Texas Democrat Rep. Chris Bell filed the complaint with the House Standards of Official Conduct Committee alleging DeLay illegally helped launder corporate campaign contribution to Republican candidates for office in Texas and took contributions from Kansas-based Westar Energy Corp. in exchange for favors.
DeLay has denied any wrongdoing, and said Bell's charges are motivated by his loss in a re-election primary battle made possible by a Texas redistricting effort spearheaded by the majority leader.