History is filled with unlikely but politically advantageous pairings: Jefferson and Adams, Churchill and Stalin, Matalin and Carville. And now, campaigning against the Northern Virginia sales tax hike proposal, there are John Grigsby, a software programmer, and Fred Warren, a farmer.

They are separated by nearly 30 years in age and -- deeply, decisively -- by politics. While they both live in Loudoun County, the farmer voted for Democrat Mark Warner and the programmer would never dream of it. The programmer shrugs his shoulders at sprawl. The farmer raises his metaphorical pitchfork.

And yet, they both rush out on the weekends clutching their signs, looking for converts to the same cause.

Politics. Bedfellows. The sales tax comes up for a vote Tuesday, and though John Grigsby and Fred Warren don't know each other, and wouldn't agree on much if they did, they are comrades in arms. The measure would boost the sales tax a half penny per dollar for transportation improvements across the car-clogged region. Both sides are fighting hard. Ads are airing, the phone banks are ringing, the stakes are on the table.

Grigsby and Warren's opposition forces have far less money than the sales tax supporters, and have tried to frame themselves as a grass-roots effort. They are powered by an unlikely mix of fiscal conservatives, anti-sprawl (aka smart growth) activists and environmentalists -- different ideologues who are happy to have each other because every vote counts, but who approach the problem from different ends.

One group resents the prospect of a tax increase, plain and simple. The other detests the influx of traffic and housing they believe new roads would bring to the region. It would be a stretch to say the two camps have more than a temporary appreciation for each other.

"I view this as an anti-tax thing," says Grigsby.

"I like to leave the old things like they are," says Warren.

Mavericks each of them, and perhaps not typical of their points of view.

Whose fight is this? Warren has been a conservationist since at least the '70s, and sees this as most definitely his. From his southern Loudoun property he can point to the house where he grew up. His family owns about 600 acres in that area; his grandchildren are the sixth generation there. He still shops at the same Winchester shoe store where his "mother and daddy" did, and proudly announces he bought his glasses from the son of the fellow who sold his mother hers.

Uneasy alliance. Perhaps it is expressed most succinctly by Grigsby's reaction when "one of the leaders of the smart growth set asked to meet with us, and nothing personal, but I refused it." The anti-sprawl set and the anti-tax set may be working on the same side, but as Grigsby sees it, they're not partners. "My desire is not to give them any credibility," he says.

Ultimately, as with so much in politics, this comes down to a fight about consistency. Who can claim to be following through on their principles? Who's being intellectually honest? And how can you be grateful to allies who are pursuing your cause for the wrong reason?

The way libertarian-leaning Grigsby sees it, the important points in this fight -- and in politics in general -- are Keep your hands out of my wallet and your nose out of my business. The referendum is yet another governmental effort to make citizens pay more for living. The smart-growthers are meddlesome, he feels, trying to make people live in high-growth areas, and around metros. Grigsby thinks people should be able to live wherever they want, smart growth be damned. That is consistency.

It's funny the way people arrive at their convictions. Wednesday evening, Grigsby eats french fries in a McDonald's in South Riding, a packet of no-tax-hike leaflets on the table, and explains his perspective. He used to be a garden-variety liberal, raised in the Cleveland area. At 17, he was an abortion-rights activist, member of the ACLU, a World Federalist and Unitarian.

"The way I grew up was, you didn't talk about things if you didn't do things about them," he says.

One day he picked up William F. Buckley's "Up From Liberalism," and that turned his head around. He started reading more. He became a Cold War hawk. He met his wife, who made a similar journey: from college-aged Reagan protester to Republican. He briefly worked for an offshoot of the Heritage Foundation, organizing anti-Soviet street theater. He has criticized county budgets he felt were too loose with money, argued on behalf of Internet filters in libraries, written letters to the editor on behalf of fiscal conservatism, and opposed "PC" hunting restrictions. He recently became an evangelical Christian.

With his wife and three young kids, Grigsby, 38, lives in rural Hillsboro, where in recent years he has witnessed an increase in housing and traffic which doesn't please him, but what can you do?

"I didn't move to Hillsboro to meet new people," Grigsby says. Still, "I can't begrudge someone else for doing that themselves and if it means more people on the road, you've got to expect that."

Fred Warren would differ. From where he stands, the battle is not to keep invisible hands from his back pocket, but construction crews from his front lawn. The improved roads the tax hike could bring would also encourage more people, he believes.

"I hope we can keep 'em outta here. We've done well so far," he says. "I wanted to make a bumper sticker, 'Don't want no' mo'!" he adds, standing on his land Thursday morning beside his Holsteins and his golden mutt, Tonto. Warren, 67, is an old-fashioned guy. "Daddy had me milking cows soon as I could reach them."

He worked as an analyst for the International Trade Commission for thirty-odd years, commuting downtown, carpooling (old values, you know), keeping his farm (dairy cows and beef cows). He retired 10 years ago. Over the years, he's resisted just about every change that's swept over this countryside. He didn't want Dulles International Airport, and he didn't want the high-tech companies that came along that way. He help successfully resist VDOT's efforts to replace an old stone bridge near his home, he says.

"I said, 'You touch one rock, you're going to have a hell of a fight on your hands.' "

This latest fracas is not over politics, says Warren, an independent, or primarily over money, though he doesn't like the idea of raising taxes. This fight is really over change -- more powerful even than feisty, bright-eyed Fred Warren.

Nowadays, there's "so much traffic everywhere and congestion, I can't find my way out of Leesburg, hardly," Warren says. If he and his wife head to Ashburn to visit one of their daughters, he makes her drive. If he goes to Washington, it's never during rush hours. If he has to shop, he prefers to go to Winchester, because it's familiar and hasn't changed as much.

"I'm like a cow," he says. "I can follow the same path."

Just who is to blame for the threat of the sales tax? It is a powerful, nefarious force -- but a different one, depending on whom you ask.

For Warren, the guilty party is the developers, who want to build more houses in the far-out suburbs and then go "laughing all the way to the bank."

For Grigsby, it is the Democrats. They want to make Northern Virginia a "sucker," paying far more than it should.

The best marriages, of course, have a common enemy. But alas, some marriages aren't destined to last.

John Grigsby opposes the Virginia sales tax increase but for a different reason than the equally opposed smart-growth activists.Farmer Fred Warren opposes the tax hike because he foresees urban sprawl.