Senate Finance Committee Chairman Max Baucus defended recommending his girlfriend for appointment as Montana's U.S. attorney, saying Saturday his one-time staff member and the former state prosecutor is "highly qualified" but eventually withdrew her nomination.

Baucus said that he began dating former state office director Melodee Hanes after they were both separated from their spouses. The Montana Democrat said they did not have an affair, but began dating while she worked for him.

Republican National Committee Chairman Michael Steele called Saturday for a Senate Ethics Committee investigation of Baucus' actions. Steele said the panel should determine "why Senator Baucus put his personal needs above those of the people of Montana."

Baucus, who is helping lead Democratic efforts to expand health care, recommended Hanes for the federal prosecutor job in February. The senator said he appointed an independent, third-party reviewer and established "an open and fair process" that resulted in her name and two others being sent, unranked, to the White House for consideration.

Baucus said he did not know whether the reviewer _ who is a long-time campaign donor to Baucus _ knew about the senator's relationship with Hanes.

The reviewer is Dana Christensen, a Montana lawyer who contributed $3,400 to Baucus's political campaigns from 1989 to 2002. Christensen's role as reviewer was disclosed Saturday night by Baucus spokesman Ty Matsdorf. A phone message left at Christensen's law office was not immediately returned.

In a statement issued by his office Saturday, Baucus said that "as we grew closer and things progressed, we knew it was time to begin the process of Mel transitioning out of my Senate office."

He said he recommended Hanes to become Montana's U.S. attorney while they were dating because she is a highly qualified prosecutor who tried more than 100 jury trials and is widely regarded as an expert in child abuse prosecution.

"Mel would have been an excellent U.S. attorney for Montana," said Baucus, 67. "I, for one, did not want her relationship with me to disqualify her from applying for the position."

Baucus' office released a resume for Hanes, which listed her only federal court experience as handling personal injury and employment discrimination cases from 1982 to 1986 as a partner in a private Iowa law firm. All of Hanes' experience as a prosecutor came in state court, mostly in child abuse cases in Iowa and Montana, according to the resume.

Hanes, 53, received prosecutor's training in 1994 at the FBI's National Law Institute in Quantico, Va., the resume states.