A government watchdog group has asked the Senate Ethics Committee to investigate whether Democratic Leader Bob Mellow's appointment to an insurance company's board should preclude him from voting on a proposed merger between Independence Blue Cross and Highmark Inc.

Mr. Mellow, D-Lackawanna, is on the board of the nonprofit Blue Cross of Northern Pennsylvania. The appointment pays $25,000 a year plus up to $36,000 in bonuses, according to Rock the Capitol, which called for the investigation Tuesday. He has been on the board since May.

Mr. Mellow has said his appointment is not a conflict of interest and that he would not recuse himself from votes related to the merger.

Sen. John Gordner, R-Montour, chairman of the Ethics Committee, said Senate rules preclude him from disclosing the status of complaints, or even if any have been filed. All complaints go through a preliminary review to determine whether there is enough substance for the six-member committee to consider it. Decisions are released only to the senator who is the subject of the complaint and the person who filed it.

Opponents say the merger would stifle competition, while the two insurance companies say it would allow them to become more efficient and to save $1 billion over six years. The savings could be used to increase coverage and stave off increases in premiums.

Mr. Mellow has spoken in favor of the merger.

Lawmakers can vote on nonbinding measures related to the merger, but the final decision rests with Insurance Commissioner Joel Ario.