He adjusts the microphone with a left hand that is missing three fingers — lost in a meat grinder on the family farm when he was 9 — and looks out at a crowd in this corner of Montana, once home to Buffalo Bill Cody, where people still like their steaks thick, taxes low and guns loaded.

“For a dirt farmer who grew up 12 miles west of Big Sandy, comin’ into a room like this — this is great,” he says. His audience cheers.

Mr Tester, 50, is a genuine, big old farm boy. He opposes gay marriage, supports the death penalty, says Hillary Clinton “doesn’t do much for me”, loves guns, hates illegal immigrants, and is the Democrat candidate for Montana’s contested US Senate seat in next month’s midterm elections.

In polls, Mr Tester narrowly leads Conrad Burns, the three-term Republican incumbent, in a state carried by President Bush in 2004 by 18 points. His appearance and his conservative stand on economic and cultural issues, sits at the heart of a new Democrat strategy to win in Republican bastions this year: full-throated populism.

“I don’t look like other senators,” Mr Tester boasts. “But isn’t it time the Senate looked a little bit more like Montana?” Montana is one of six Senate seats that the Democrats have to win to retake control of the chamber. Most of those contests are in Republican or swing states, and in nearly all of them the party is fielding candidates who, like Mr Tester, are culturally conservative — well to the right of Democrats’ grassroots activists — and economically populist. They are anti-free trade and protectionist, rail against the outsourcing of jobs to China, but also advocate lowering taxes and balancing the federal budget.

“Just look at Jon Tester — the buzz cut, the big gut. He is Montana,” said Larry Sabato, a political analyst. “Does he look like a liberal Democrat? No chance. He is a populist. And that’s why I think he’s going to win. The Democrats have woken up. They are tired of losing. They have caught up with reality. The country is largely conservative, and they are making the changes needed to win.”

In addition to Mr Tester, other Democrat Senate hopefuls with good chances of beating Republican opponents include Jim Webb in Virginia, Harold Ford in Tennessee, Sherrod Brown in Ohio, Claire McCaskill in Missouri, and Bob Casey in Pennsylvania. Messrs Brown, Casey and Tester are unapologetic economic populists; Messrs Ford, Webb and Tester take Republican stands on cultural issues.

Mr Tester, like the other Democrat candidates, is also being helped by the Republicans’ myriad political problems, including Iraq, corruption and scandal — and nowhere has this been more colourfully on display than in Montana.

Mr Burns was once the embodiment of Big Sky Country, as Montana — a state of just 900,000 — is known. He picks his teeth with a pocket-knife, chews tobacco and tells earthy jokes. But in January it emerged that he had taken $150,000 in contributions from the disgraced Republican lobbyist Jack Abramoff, who pleaded guilty last year to bribing politicians. Mr Tester has hammered away on the issue for months, accusing Mr Burns of what in Montana is political apostasy — “going Washington”.

Mr Burns has also made several blunders. He insulted local firemen, saying that they did a “piss-poor” job fighting a wildfire; he called Arab oil sheikhs “ragheads”, and suggested all taxi drivers were terrorists.

But it is Mr Tester’s ability to out-Montana Mr Burns and his populist embrace of Republican issues that has been crucial. Should he win, Montana’s two senators and its Governor, Brian Schweitzer, a prairie populist, will all be Democrats for the first time since 1989. A Tester victory will bolster claims by the party’s centrists that the only way to gain ground in Republican strongholds is to run as conservative Democrats. It will also give Capitol Hill a protectionist lurch, pitting supporters of a global economy — most leading Republicans — against many Democrats, including Hillary Clinton, who are embracing the populism of “fair wages” for workers.

“I do some of my best thinking on my tractor,” Mr Tester told The Times. “I say what I say because I’m a Montanan. If the national folks in Washington don’t agree wi’ that, I guess I’m different from them.”

Times Recommends

• Times Charity Appeal: SolarAid
• Is it Black Monday all over again for Dubai?
• Behind the scenes at the biggest deal