Republicans on Saturday called on the Senate Ethics Committee to investigate the disclosure by a senior Democrat that he had recommended his girlfriend to be U.S. attorney.

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

But the Republican National Committee said the revelation "demands the attention of the Senate Ethics Committee."

"Today's report that Senator Max Baucus used his Senate office to advance a taxpayer funded appointment for his staff-member girlfriend raises a whole host of ethical questions," RNC Chairman Michael Steele said in a written statement.

"They should hold a hearing to identify who was involved in this process, what they knew and when they knew it, and why Sen. Baucus put his personal needs above those of the people of Montana."

Baucus said that he and former state office director Melodee Hanes began dating 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.

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

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," Baucus said. "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, according to the resume.

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

Baucus, who is helping lead Democratic efforts to expand health care, nominated Hanes for the federal prosecutor job in March. He 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.

But Hanes later withdrew, saying earlier this year she did so because she received other opportunities she couldn't pass up. Hanes now works for the Justice Department, hired earlier this year as acting deputy administrator for policy in the Office of Juvenile Justice and Delinquency Prevention.

"In the end, we decided it would be best for Mel to withdraw her name from consideration," Baucus said in his statement Saturday. "That also allowed us to live together in Washington."

He said she received her Justice job after applying "independently," and "not surprisingly to anyone who's looked at her resume, got the DOJ job on her merit."

Baucus' office released details of his relationship with Hanes late Friday night in response to questions from Mainjustice.com, a news Web site covering the Justice Department that first reported the circumstances of Hanes' nomination.

Baucus has played a major role in managing the Democrats' health care overhaul efforts. He led Senate debate Saturday on the health bill, receiving a nod of support from Senate Majority Leader Harry Reid.

"Max is a good friend, an outstanding senator and he has my full support," Reid, D-Nev., said in a statement released by his spokesman.

Republican Sen. Lisa Murkowski of Alaska said she didn't think the issue would affect Baucus' leadership in the health care debate. "I don't think it's going to distract from the substance of the debate," she said.

Baucus and his ex-wife Wanda announced last April that they planned to divorce after 25 years of marriage, his second. In a joint statement, they said they had "parted ways amicably and with mutual respect."

Hanes started working for Baucus in 2002 and was his state director before leaving his office for the Justice Department position.

"Mel and I have a wonderful relationship. We are living together and enjoying spending time with each other and our families. I'm as happy as I've ever been," Baucus said in his statement.

President Barack Obama eventually nominated Helena attorney Michael Cotter for the U.S. attorney post, which supervises prosecutors of all federal crimes committed in Montana and the state's seven Indian reservations. Cotter is awaiting Senate confirmation.

Word of Hanes' nomination follows other recent disclosures of romantic liaisons by political leaders, including South Carolina Gov. Mark Sanford, Sen. John Ensign, R-Nev., and two-time Democratic presidential hopeful John Edwards.

Sanford faces a possible impeachment following his affair with a woman in Argentina. Ensign, who has acknowledged in June to having an affair with a former member of his campaign staff, has made it clear he intends to serve out his second term. Edwards' political career was damaged when he acknowledged last year he had an affair with a videographer in 2006. The admission came just months after Edwards dropped his second presidential bid.

Baucus was elected to the Montana House in 1973 and to the U.S. House in 1974 and 1976. He was elected to the U.S. Senate in 1978 at age 36, and his current term runs until 2014.

The senator has played increasingly visible roles in Congress, sometimes willing to buck his Democratic Party on certain issues. He seems to take the position that the state that sent him to the Senate for five terms is fundamentally conservative and its voters want someone willing to vote outside the party line.