After three days on the road talking to voters, Jon Tester finally made it home. He rumbled down seven miles of dirt road and pulled up to his wheat farm. He untied his tie, changed into jeans and climbed into his tractor.

Then Tester flipped on the radio. Even here, at peace on his wind-swept homestead — 48 miles from the closest McDonald’s and a world removed from Washington — Tester couldn’t escape his day job.

“Why does Senator Tester side with the big banks and not us?” a man asked over harrowing music in a radio ad.

Listening inside his tractor’s cockpit, the Democratic senator muttered a barnyard expletive and said, “It’s already started.”

What’s started in Montana is a high-stakes 2012 race that will test the staying power of rural Western Democrats in the Obama era and help determine which party will lead the U.S. Senate.

Tester is among the class of Democratic majority-makers: centrists who, in 2006, rode a wave of dissatisfaction with President George W. Bush and a backlash over the Iraq war to win seats in previously Republican territory, propelling their party to majority status in both houses of Congress.

In 2012, toss-up contests in a trio of states — Missouri, Montana and Virginia — could decide whether Democrats, who this cycle have to defend more than twice as many seats as Republicans, can maintain their 53 to 47 Senate majority.

“These three states will probably determine the control of the United States Senate,” said Stuart Rothenberg, a nonpartisan political analyst. “It’s that simple.”

In all three, the races, so far, have been shaped by the Democratic candidates’ connections to President Obama. In the fiscal debate, Tester and others are seizing opportunities to establish distance.

In 2006, Tester said he would carry to Congress the pragmatism he learned while tending to his family farm. Now, after having voted to pass much of Obama’s ambitious agenda — chiefly, the health-care overhaul that is unpopular here — the 6-foot, 300-pound hulk of a senator is at risk of becoming an endangered species.

Tester faces a formidable challenge from Rep. Denny Rehberg (R), who, as Montana’s only congressman, has won election statewide six times.

Like Sen. Claire McCaskill (D-Mo.) and Timothy M. Kaine, a Democratic candidate for Senate in Virginia, Tester is emphasizing the narrative that brought him early political success — in his case, an “I’m just a dirt farmer” biography — to demonstrate that he’s a different kind of Democrat than the one who occupies the White House.

“I’m from Montana, and I look at things from a rural perspective. Barack is from Chicago and doesn’t look at things from that perspective,” Tester said over the chimes of a cuckoo clock in an interview at a dinette table in his house, which sits on 1,800 acres of Big Sandy plains that his grandparents settled a century ago.

“Washington, D.C., can be a bit artificial, but this ain’t artificial. And when you start thinking it is artificial, the combine and the tractor let you know. They don’t give a damn. They’ll break down when they want to break down, and they don’t care if you’re a senator or not.”

Distinctive look

In 2006, Tester’s campaign was as much about his distinctive look as about the ethics problems of the Republican senator he unseated, Conrad Burns. Tester talks about the three fingers he lost while operating the family’s meat grinder at age 9 — “It changed me from a saxophone player to a trumpet player,” he quipped — as evidence of a strong work ethic. His flattop haircut symbolized the endlessly flat and treeless backcountry near the Canadian border, where he and his wife, Sharla, grow organic wheat, barley and peas.

“I don’t look like the other senators, but isn’t it time the Senate look a little bit more like Montana?” Tester would ask in television ads, a dirty barn coat stretched over his potbelly.

Tester, who had served eight years in the part-time state Senate, won by one of 2006’s narrowest margins: 3,562 votes.

Once in Washington, Tester voted for the $787 billion stimulus bill and the health-care overhaul. Republicans are using that against him in a state whose voters traditionally oppose some federal mandates. (Although, notably, voters here support agricultural subsidies.)

“He’s got this carefully crafted image from 2006 that is completely shattered after four years of his record,” said Erik Iverson, Rehberg’s campaign consultant. “He’s got a conservative haircut, but he’s got liberal values.”

In a February video announcing his campaign, Rehberg said: “I’m running because of what I’ve heard from listening to the people of Montana, especially over the last two years as the liberal know-it-alls have taken over Washington, D.C. — in a big way.” He declined requests for an interview.

With Obama on the 2012 ballot, Rehberg’s message could resonate. Since 1952, Montana has voted for only two Democratic presidential candidates.

Outside of Missoula, a liberal college town, and Butte, historically a labor stronghold, Montana is overwhelmingly Republican. To win, Tester will have to carry those cities by wide margins, minimize losses in the more conservative cities of Billings and Great Falls, and stay competitive with Rehberg in rural areas, where he found support in 2006.

Health-care law an issue

The biggest liability for Democrats in Montana, Missouri and Virginia could be their support for Obama’s health-care law. After narrowly winning her seat in the Republican-leaning swing state of Missouri, McCaskill had been one of Obama’s most vocal supporters. Now she is sponsoring a bill with a Republican senator to cap spending; many Democrats oppose it because the binding cap would apply to Social Security.

Similarly, Kaine crisscrossed the country promoting Obama and his agenda as Democratic National Committee chairman for two years, only to run for Senate by highlighting instead his relatively centrist record as Virginia’s governor.

In Montana, Tester has taken heat for his health-care vote. He defends it with a personal reason: He and his wife went without insurance for years, including during the birth of a child, because they couldn’t afford it.

“Is it going to break this country? Far from it,” Tester said about the health-care law, raising his voice. “Are there things we need to do to make it better? Absolutely. But there’s so much bad information out there and so much paranoia about it that, quite frankly, if I walked into town right now, you probably wouldn’t find a lot of people raising the pompoms.”

At times, Tester has not gone along with his party. He was one of the few Senate Democrats to vote against the 2008 Troubled Assets Relief Program for banks. In December, he voted against the DREAM Act, which would have created a pathway to citizenship for children of illegal immigrants, angering activists among the liberal netroots activist community that helped propel his first campaign.

And everywhere Tester went one week in April, from coffee shops to radio studios to microbreweries, he talked with blunt machismo about wolves. It’s a classic states’ rights victory: He removed gray wolves in Montana and other Western states from the endangered-species list. Environmentalists opposed it, but Montana’s ranchers and outdoorsmen cheered.

“Bottom line is, we’re able to hunt the wolves now,” Tester said.

Race a dead heat

The Montana race has jelled early. The most recent public poll showed Tester and Rehberg in a statistical dead heat. They do not yet have primary opponents and are raking in cash — huge sums for a rural state where television airtime is relatively cheap. In the first quarter of 2011, Tester raised more than $1.1 million, while Rehberg raised $580,000 and transferred about $500,000 from his House campaign account. At the end of the quarter, Tester had nearly $1.45 million in cash on hand, and Rehberg had $933,000.

Republicans have attacked Tester’s big haul, pointing to an analysis by the Hill newspaper showing that he collected nearly $60,000 in contributions from credit card companies in the 17 days after he introduced legislation to delay new regulations on debit-card swipe fees.

Tester’s proposal would postpone implementation of a rule that caps the fees banks can charge retailers for debit-card transactions at 12 cents. He said the delay would protect community banks that couldn’t afford to provide free debit-card privileges if retailers paid such nominal fees. But Republicans say Tester’s plan helps big banks, too.

The conservative group Americans for Job Security is airing a 60-second advertisement on Montana radio stations alleging that Tester sides with Wall Street.

When some high school students asked Tester about the ad, he said, “It’s totally bogus.” Being a politician, he told them, is like “branding calves. Most of the time it’ll be good, and every once in a while you’ll be kicked in places you don’t want to get kicked.”

This raises a paradox: Why does a man who says he is at peace harvesting wheat and loathes the ways of Washington want to return there for another six years?

Back at his farmhouse, Tester said: “I’m not going to be there when I’m an old man. I ain’t wired for that. But you can’t make the kind of changes to give opportunities to kids and move the country forward sitting on that tractor out there. You can in Washington, D.C.”