It is only political blood that will be spilt, but what is being played out is a unique duel the likes of which this frontier state has not seen for generations. At stake are the public careers of both men but also, more fundamentally, the fate of swathes of mountain wilderness.
The fight was started by a mathematical formula. A 1990 census showed that because its population growth had not kept up with the national average, Montana no longer had enough people to keep its two seats in the United States Congress. The courts decreed that its two congressional districts would have to be rolled into one.
And so it is that Pat Williams, a traditional Democrat who has represented Montana's mountainous West region for 14 years, and Ron Marlenee, a reactionary Republican whose constituency has been the high plains in the East for 16 years, are fighting to assume responsibility for a state that has a population of 800,000 and stretches more than 500 miles from east to west.
For Montanans, the choice is not just between two starkly different personalities - one, Mr Williams, a rumpled, self-deprecating former teacher and the other, Mr Marlenee, a bluntly-spoken, barrel-chested rancher - but also between two contrasting political philosophies. With a month before election day, they are neck-and-neck in the polls.
'It is without question the most important race in Montana's modern history, that boils down to a face-off between the prairies East and the timber- resources West,' said Todd Wilkinson, an environmental writer in the mountain town of Bozeman. 'Marlenee is the template of sentiments in the East, and the same is true of Williams for the West.'
The policy differences between the two are manifold. Mr Williams, a New Deal Democrat, believes in the role of federal government and public investment to promote economic activity. He also has a stong environmental record.
His support in his old western constituency has grown from the natural concern of mountain-dwellers for the preservation of their surroundings and the unionising history of an area that was once dependent on mining.
Mr Marlenee is an apostle of Reaganomics, who peddles trickle-down economics and the emasculation of government. His disdain for environmentalists - whom he variously calls 'fern- feelers', 'flamingo-feather-counters' and 'prairie-fairies' - is legendary. He stands for the frontier creed, still widely held by plains ranchers, that the land you own is yours to do what you like with, and federal regulations be damned.
Caught between these philosophies is Montana's visually stunning heritage of millions of acres of virgin forest, mostly in valleys among the Rocky Mountains. In the last days of the outgoing Congress, Mr Williams and Mr Marlenee are slugging it out over two competing 'wilderness bills' that would set some parts of this land aside for permanent protection and other parts for timber, mining and recreational exploitation.
For environmentalists like Mr Wilkinson, the importance of a Williams victory, as champion of federal protection of these areas, is fundamental. 'The history of the state of Montana is that of a Third World resource colony. The only thing stopping corporate interests from coming in and carving us up and taking away the profits when they leave are federal laws,' he argued.
No place symbolises the environmental hazards quite so vividly as the town of Butte, the birthplace of Mr Williams and once the copper-mining capital of the West. At the turn of the century, when the Anaconda Mining Co had drawn 100,000 people to the town, it was said to sit on the 'richest hill on earth'. Now, its population down to 30,000 and its mines all but stripped, it lies in the shadow of mountains gouged into giant gravel terraces, while at its edge, a crater that measures a mile-and-a-half across and 1,800ft deep, is filling with poisonous water at the rate of 7 million gallons a day.
Mr Williams, campaigning recently in Butte, pointed to the wilderness issue to underscore what he believes is at stake in this race. 'Montana is in a very real way approaching the brow of America's final hill. Montana now is how America used to be,' he said in an interview. 'We still have time to determine our own destiny - Ron sees that destiny very differently than I do. I would allow sensible use of our natural resources, while protecting the value of our scenery. Ron would run the remaining forest through the mill.'
Mr Marlenee rejects as 'preposterous' accusations that he would sacrifice scenery for economic gain willy-nilly but ridicules what he sees as his opponent's extremism. 'You don't have to put people out of work, you don't have to bankrupt local communities, you don't have to shut up businesses, to be environmentally sensitive,' he said. 'All you have to be is balanced.'
In a time of economic hardship and in a state so dependent on natural resources, Mr Williams knows his enviromental message carries considerable risk. But his vote will be swollen by an important recent influx of often young, environmentally-conscious settlers from other states, notably California, who have come to 'Big Sky' country in search of America's last mountain paradise. Valleys around Bozeman are becoming virtual extensions of Hollywood, providing ranch homes to such folk as Jane Fonda and Robert Redford.
Mr Williams often reminds supporters of Montana's own description of itself as the 'last best place' in America. 'All I'm trying to do,' he says, 'is protect the best of the last best place.'