Colorado: High stakes in high altitude state
Americans are voting in mid-term elections which will decide who controls the Senate and pave the way for the 2016 race for the White House.
It's only two hours from Colorado Springs to Boulder, driving north with the jagged line of the Rocky Mountains to the west, but you're travelling between two Americas.
Someone described the state the other day as the petri dish of American politics - a place where different cultures are growing, with no-one quite sure what the result will be.
In the wide open spaces of the west, you see battle lines drawn on some of the great arguments that dictate the tide of politics in the United States: it's where competing ideas of freedom, and the role of the constitution, are set against each other.
Start in Colorado Springs, south of Denver, a place that epitomises for liberals the crusading conservative movement, and its power.
Focus on the Family has a handsome and opulent headquarters looking down the valley along which the city sprawls, and the organisation is one of the pillars of social conservatism that has colonised this part of the state - a place where you'll find religious fervour, political muscle and utter determination.
More than 80 evangelical organisations operate from here, and it's the headquarters of their fight against liberalism.
For Jim Daly, president of the Focus on the Family campaign, it's a never-ending struggle.
But I found him acknowledging failure as well as success.
Far from the super-confident absolutist that you might expect, he confessed that conservatives haven't always been winning the argument.
He was frank with me about same-sex marriage - acknowledging that with more than 30 states having legislated, and the Supreme Court apparently not interested in interfering, the battle to stop it had been lost. Older voters remain opposed, but for the under-45s there's approval by more than two to one.
To my surprise, I found him unbothered. I sense that he knew that this would be the outcome.
But on abortion: no surrender.
He didn't expect any success in overturning Roe v Wade, the Supreme Court decision in the 1970s that allowed abortion, although he'd like to see it reversed, but he believed there was a cultural shift in America that would "hollow it out".
It was a conversation, intriguingly, in which he wanted to appear flexible (saying, for example, that hard line rhetoric on social questions "didn't move the needle").
He spoke about trying to find some common ground with liberal groups - on adoption, for example there's been some progress - but this was still politics in the raw.
It's from here that much of the toxic rhetoric about a Godless and misguided America has emerged. They talk about it as a cultural and constitutional heritage that must be defended.
Two hours north, beyond Denver, and in the lee of the high Rockies, the constitution is being put to a different use, by people who'd find themselves deeply out of sympathy with Mr Daly.
Colorado has legalised marijuana, and they talk of it in Boulder as a victory for the American way.
I met a customer coming out of one of the shops where they sell cigarettes, tubs of marijuana truffles, and display all kinds of varieties as if they were a greengrocer's.
"I make a ton of money for the state of Colorado," the manager told me, through the tax that's imposed on every joint and hash brownie.
Did he think that would mean that more states would follow them?
He laughed. Wasn't it obvious?
The governor, he supposed, was very pleased with him. and when they looked at the tax revenues, he thought other states would do it if they thought their voters would approve.
I was struck, as always, by the passion with which liberals and conservatives fight for the pieces of the constitution that speak to them about America. In a sense they never leave the fundamental debate: what should the constitution mean now?
On gun rights, for example, conservatives will try to stop any encroachment on what are known as "second amendment rights" - the right to bear arms.
The meaning of that amendment is hotly disputed among constitutionalists, but never mind.
Conservatives managed successfully to throw out two state senators last year - by means of the recall law that allows them to be defenestrated in mid-term - because they had proposed modest regulations in the Colorado legislature that would have limited the size of rifle magazines to 10 rounds and insisted on background checks on anyone buying a gun.
The point is the force of belief.
Listening to Senator Mark Udall, fighting to hold on to his seat against a strong Republican tide, it was striking how much this campaign, as so often in the United States, was coming back to fundamentals - pro-choice against pro-life on abortion, Obamacare versus a market system on health.
But there's one issue in Colorado that's fascinating, because it disturbs both sides.
It's a state in which everyone values the environment, a precious landscape and one that's needed by ranchers and farmers.
So Coloradans are alarmed by the increased incidence of extreme weather events - especially bush fires caused by drought, and flash floods - and they wonder about climate change.
For conservatives, climate science is regarded with extreme scepticism and even by some religious groups as an interference with God's plan, but they're aware of the public alarm at the predictions of changes in weather patterns that could have a profound effect.
They're alert to the subject, because in a mountain state the weather matters more.
Liberals are torn too. Colorado has opened itself up enthusiastically to fracking, the extraction of oil and gas under pressure to find reserves hitherto unexploited.
The claim by the energy companies is that it offers America the valuable prize of energy independence from the Middle East and will keep consumer prices low.
But for some, the presence of around 50,000 fracking sites across the state - about half of them in Weld County near Denver - is unacceptable.
The opponents believe that they are getting the first scientific evidence that the chemicals used in tracking are leaking, and are harmful to health.
The energy companies are emphatic this is not true, and over the net few years they will battle it out with statistics, survey by survey.
Meanwhile, there are many natural Democrats who are pulled towards the practical arguments - jobs and investment - while others remain unconvinced by the fracking arguments, and hostile to the rhetoric and the tactics of the big companies who're moving in and setting up fracking sites not only in wasteland, but near reservoirs and schools too.
All this makes Colorado a political laboratory. The Democrat governor, John Hickenlooper, is fighting a tough race and, in the run-up to polling day Mr Udall appears to be behind.
Colorado, which has become a swing state in recent years after many years as a solid Republican place, is unpredictable, but on Tuesday night might well abandon Barack Obama's party and turn red again.
But more interesting than the result is the fact that you can't leave there without reflecting on the extent to which voters are moved, now and in the preparations for the next presidential campaign in 2016, not so much by day-to-day employment figures or economic projections, but by belief.
Everyone says they're fed up with politics and politicians, but they care.
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