Rep. Denny Rehberg (R-Mont.) will challenge Sen. Jon TesterJon TesterPoll: Senate should confirm Gorsuch A guide to the committees: Senate GOP loses top Senate contenders MORE (D-Mont.) in 2012, giving Republicans another solid candidate in a race that will be one of the party's top targets next year.  

Rehberg will officially get into the race this weekend at a GOP dinner in Montana, a Republican source with knowledge of Rehberg's plans confirmed to The Ballot Box. 

His entry into the race was first reported by Roll Call late Monday. 

Rehberg's candidacy is more good news for Senate Republicans looking to take back the majority in the upper chamber next year. In his sixth term occupying the state's at-large congressional seat, Rehberg has a strong statewide profile and the ability to raise the funds needed for a Senate race.

It will be the second Senate race of Rehberg's career — he launched an unsuccessful challenge to Sen. Max BaucusMax BaucusFive reasons why Tillerson is likely to get through Business groups express support for Branstad nomination The mysterious sealed opioid report fuels speculation MORE (D-Mont.) in 1996, before he was elected to the House. 

The latest campaign filings show Tester with just a modest cash edge at the start of the year. The Democrat has some $562,000 cash on hand, while Rehberg reported $553,000 on hand.

Republican businessman Steve Daines is already in the race against Tester and posted a solid fundraising start, pulling in some $225,000 since getting in. With Rehberg now in the Senate race, though, Daines is reportedly looking at a run for the state's at-large House seat instead.

-Updated at 10:05 a.m.