Updated 4:15 p.m. | The Senate’s confirmation Thursday of Sen. Max Baucus, D-Mont., as ambassador to China immediately sets off the need for an appointment to replace him.

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The onus falls on Democratic Gov. Steve Bullock, who must choose someone to fill out the remaining year of Baucus’ term. The governor has scheduled a press conference for Friday at noon ET.  

Lt. Gov. John Walsh, who was elected on the same ticket as Bullock in 2012, is already running for Senate. While he’s the odds-on favorite to be appointed, his selection to replace Baucus is no sure thing.  

An ally of the administration confirmed to CQ Roll Call that Bullock “has gone through a process, been very hands on, but kept it really close to him and top aides — he’s watched failed appointments in the past and he’s not the kind of guy to make stupid errors.  

“He’s a lawyer and he’s thorough,” the source continued. “I don’t think anyone would be surprised if Bullock picks someone close to him — his lieutenant governor or someone from the cabinet — but I would be surprised if he does it without having spent a great amount of time weighing pros and cons.” The advantages for Walsh in being appointed include increasing his name recognition and fundraising as a sitting senator.  

Walsh, who raised $583,000 in the fourth quarter, is backed by national Democrats and is the front-runner for the nomination in the June 3 primary. He faces former Lt. Gov. John Bohlinger and rancher Dirk Adams.  

GOP Rep. Steve Daines, who raised more than $1 million in the fourth quarter and had $1.9 million in cash on hand at the end of the year, is also running.  

The race is rated Tossup/Tilts-Republican by Rothenberg Political Report/Roll Call.