Democrat Jon Tester has tried to steer a middle course in his first term in the Senate between safeguarding Montana's natural beauty and protecting its economic interests as he sees them -- whether that means allowing wolf hunting or opening new areas of the forest to logging. But Republicans are betting that the senator has failed to prove to Montanans that he will buck his party to protect them from environmental regulations, which many oppose both on principle and because the state's economy depends on industries that demand ready access to natural resources, such as agriculture, energy production, timber and wilderness recreation. They hope this will help Rep. Denny Rehberg (R) defeat Tester in what is already one of the marquee political matchups of 2012.