(CBS NEWS) GREAT FALLS, Mont. - One of the most vulnerable Democratic seats in the battle for the United States Senate is occupied by Montana's Jon Tester, who ousted an incumbent in 2006 by only 3,562 votes out of 400,000 ballots cast, the slimmest margin of victory of any Senate race that year.
In 2008, President Obama came within 11,000 votes of snatching the state from John McCain's column. This isn't as Democratic a year.
"It's no secret the President is going to lose Montana," Tester said in an interview. "Montanans pride themselves on splitting tickets."
With Tester, Democrats hold the Senate majority by four seats, 53-47, but the party is in danger of losing control of the chamber to Republicans.
Though his is one of a dozen races rated as toss-ups going into the final week of the campaign, Tester feels no special responsibility to protect Democratic control.
"I don't know what's going to happen in states like North Dakota and Missouri and Ohio, but I do know that if I am re-elected to the U.S. Senate, Montanans will get the representation they deserve," he said.
There are not a lot of United States Senators like Tester. At 55, he's a real farmer who lives at the end of a dirt road in a rural town called Big Sandy, a 75-minute drive north of Great Falls, a city of 58,000, where he gets a regular buzz haircut for nine dollars.
He and his wife of 35 years, Sharla, farm wheat on the same land Tester's grandfather homesteaded and where a century-old red wood barn still stands.
Tester is not in lockstep with the party. National Journal rates his voting record in the middle of the ideological axis, about 50 percent liberal-conservative on economic, social, and foreign policy issues.
He supports gun rights, advocated dropping wolves from the endangered species list, and opposed new labor regulations for youthful farm workers.
Still, his Republican challenger, six-term congressman Denny Rehberg has tried to the race into a referendum on President Obama.
"It's a referendum on Jon Tester, who votes with the Obama administration, I think, against the values and principles of the people of Montana," Rehberg said in an interview.
One of his TV ads features a pair of identical twins asking, "Having trouble telling us apart? Try Jon Tester and Barack Obama."
The twins assert Tester has supported the White House on nine out of every ten votes.
"It's not factual," Tester said. "The bottom line is I don't agree with (my) wife 93% of the time."
But Tester did support two of the President's biggest legislative initiatives. First was the $800 billion economic stimulus passed early in Obama's term. Rehberg said it was padded with wasteful spending.
"There's bypasses and road projects, and electrical transmission projects that put people to work," Tester said. "For my opponent to walk out and gave the same old phrase, 'failed stimulus,' look around."
Tester said the nation was losing 800,000 jobs a month before the stimulus bill passed but has now experienced 31 months of private sector job growth.
"The truth is we were on the cusp of going into a depression similar to the 1930s, and we had to do something," Tester said.
Rehberg, who helped lead the House of Representatives' opposition to Obama's health care reform, would repeal it. In June, the Supreme Court upheld the constitutionality of the individual mandate that everyone obtain insurance. Rehberg believes the plan did too little to control rising health care costs.
"If you are seriously going to consider controlling the cost of health care, then you don't do it by leaving tort reform or defensive medicine out of the picture," Rehberg said. "And it's not the lawsuit itself; it's the fear of the lawsuit. It's doctors who do two procedures -- maybe it's an X-ray -- rather than one. Or it's a doctor who puts somebody in overnight in a hospital, checks them in, rather than an outpatient procedure, just to be on the safe side."
Rehberg advocates alternatives to the individual mandate to expand access to care, such as association health care plans, which let businesses band together to negotiate lower premiums, or family practice residency programs which can expand the number of doctors available to treat the insured.
Tester defends his vote for the Obama health care plan, which also banned insurance companies from imposing lifetime caps on health care, barred them from denying coverage for preexisting conditions, and required them to allow parents to cover their children as dependents until the age of 26.
"As it's implemented and people see the advantages, see more completion in the marketplace, see health care costs starting to flatten out already, I think they'll accept it," Tester said.
Rehberg, 56, is fifth generation Montanan who grew up on a ranch near Billings, the state's most populous city, with 104,000 people. In the past decade, he divided more than 800 acres of his land into high-end homes called Rehberg Ranch Estates, managed with his wife, Jan, and they became multimillionaires.
Rehberg is as well known in Montana as Tester, since he's the only House member for a state with fewer than a million residents. He too represents all 56 counties of this massive and sparsely populated state, 4th in land mass and 44th in population.
"If we want to turn our economy around, we really need to liberate Main Street," Rehberg told a recent gathering at a Great Falls pizza restaurant. "We all know that government doesn't create jobs, small businesses do; people do."
Rehberg's lament, echoed by a lot of Capitol Hill Republicans, is the Democratic Senate is where good Republican ideas passed by the House go to die.
"Getting government off the back of small business and giving us certainty within our tax structure. Learn to live within our means, balance our budget, tighten our belts like the American public has to," Rehberg said in an interview. "I don't want to be in Congress if I can't make a difference."
Besides a combined $20 million Tester and Rehberg have raised for their race, another $15 million from outside interest groups has poured into the state, saturating the airwaves. For 18 months, this pastoral landscape has been pierced by the sounds of a bitter campaign.
Rehberg said it is necessary to change the Senate majority to end Washington gridlock, but also sounded a conciliatory tone.
"I'm willing to work with anybody, I'll roll up my sleeves, and I'll work with anybody who will work with me," he said.
Tester said in a way it doesn't matter who's running the U.S. Senate or House.
"There are some really good people in Washington, D.C., on both sides of the aisle," Tester said. "If they're not willing to put politics aside, with the important decisions that have to be made that surround deficit and debt, surround health care, surround energy, foreign policy, we're not going to get anything done."