Rep. Denny Rehberg has been awarded the chairmanship of a key Appropriations subcommittee, a promotion that could have profound implications for the Montana Republican’s Senate ambitions in 2012.

Rehberg was largely thought to be weighing a run against first-term Sen. Jon Tester (D) in the coming cycle. Rehberg will lead the Appropriations Subcommittee on Health and Human Services going forward. The panel is expected to oversee GOP efforts to repeal, or strip funding from, President Barack Obama’s health care overhaul in the new Congress.

The promotion gives the six-term incumbent a prominent platform from which to jump into the Senate race, or to criticize Tester over his vote for health care reform. But it also gives Rehberg tremendous influence on a committee that largely controls Congress’ purse strings, a position he may be reluctant to give up because of its potential to directly benefit his constituents.

“Denny is focused on doing the job the overwhelming majority of Montana voters sent him to Washington to do,” spokesman Jed Link told Roll Call earlier in the week in response to questions about Rehberg’s Senate prospects in 2012.

The committee change is yet another example of how the House Republican takeover may complicate the GOP’s fight to assume Senate control in 2012.