U.S. Vice President Joe Biden administered the oath of office in the Senate chamber Tuesday to John Walsh, who is replacing Max Baucus, the former Democratic senator tapped by President Barack Obama to serve as U.S. ambassador to China. The Senate confirmed Baucus' nomination last week. Democratic Governor Steve Bullock appointed Walsh, the state's lieutenant governor, to replace Baucus. Walsh had announced his candidacy for the seat after Baucus said last year that he would retire after six terms. Walsh is likely to face Republican Representative Steve Daines in the contest for the open seat.