WASHINGTON  Senator Max Baucus, a powerful committee chairman and a chief architect of the Democratic health care overhaul, acknowledged Saturday that he had recommended the Obama administration appoint a woman he was dating to serve as the federal prosecutor in his home state, Montana.

In response to news media inquiries, Mr. Baucus, a Democrat and the chairman of the Finance Committee, said that he had already begun a relationship with the woman, Melodee Hanes, the director of his state operations, in February when he submitted her name along with two others as candidates to serve as United States attorney for the state.

When the relationship intensified, Mr. Baucus said, he and Ms. Hanes agreed jointly in March that she would withdraw from consideration, and another person was eventually nominated. Ms. Hanes, 53, an experienced prosecutor, then took a job at the Justice Department. She and Mr. Baucus, both divorced, now live together.

“It just made sense for her not to be a candidate because we were close,” Mr. Baucus, 67, said Saturday as he met with reporters just outside the Senate chamber. He said Ms. Hanes began looking for a new position after they agreed she should no longer work in the Senate office because of their relationship.