Schweitzer is Democrats' best hope at winning retiring Sen. Max BaucusMax Sieben BaucusSteady American leadership is key to success with China and Korea Orrin Hatch, ‘a tough old bird,’ got a lot done in the Senate Canada crossing fine line between fair and unfair trade MORE's (D-Mont.) seat. He told The Hill shortly after Baucus's retirement that he was looking at a run, but has been silent since — which has made some Democrats nervous.

But Tester isn't one of them, despite not having talked to Schweitzer in some time.

"I will tell you, I haven't talked to Brian in six months, but the truth is he's working on a mine issue right now. I anticipate, and my crystal ball is still a little cloudy, but I anticipate he's going to get in to this thing."

If the popular former governor runs he'll likely have the edge in a race — though former Gov. Marc Racicot (R), who hasn't ruled out a bid, polls strongly against Schweitzer. 

But if he sits it out, Democrats will face an uphill battle to hold the seat, giving the GOP an easier path to winning back control of the Senate.

Watch the video: 

Visit for breaking news, world news, and news about the economy