DENVER, Colorado — down at the 16th Street mall, the girls in pink are out collecting signatures. One or two guys too, but it’s mainly teenagers and young women, big windcheaters with “no to 67” scrawled across the garish front. Mid-afternoon in the centre of the Mile-High City, the mall lined with restored red brick buildings and cute coffee houses and microbrew pubs.

Funky little town, liberal heartland, surging with tech jobs and the “new west” ethos, and the “no to 67” crowd — Planned Parenthood, uni groups, people down from ultra-Left Boulder — is in a fight to head off ballot measure 67, which would amend the state’s constitution to recognise “personhood” as beginning at conception. The move would of course criminalise all abortion whatsoever, as well as the morning-after pill — and open the way for the prosecution of women who miscarry through “negligent acts”. It’s a crucial battle, a Thermopylae, a Stalingrad for women’s rights, indeed for bodily autonomy, and so for Colorado’s progressive, it’s drop any other cause,  see them off, all bodies to the front.

And this is the third time they’ve had to do it.

Yes, the personhood amendment has been proposed and soundly rejected in two previous elections, each time with a 70% vote against. It’s a tactic that’s been tried elsewhere by the Right, and largely abandoned, with both mainline and evangelical churches rejecting it as a counterproductive tactic. But in Colorado, a state with a huge number of fundamentalists — largely focused around some megachurches and the Focus on the Family group in Colorado Springs, south of Denver — it just won’t go away, and there is no capacity within the state’s special measures system to delay a return to the ballot paper, and treat the question as settled, for a time. So every election, old activists must put off other causes, and a new phalanx of young activists must be recruited to battle it afresh.

That is not without its advantages for progressives — since it politicises one cohort after another with a very immediate threat to their rights. The young women in the mall are white and black and Asian, but they’re all middle class, college kids with that classic double, vocal fry (that sort of throttled Heathers-style speech) together with rising inflection, which takes the edge off the politics somewhat.

“Like, this is outrageous, K” says Sara, holding the clipboard while I sign, Senator Eric Abetz, hobbit, Tasmania. “My uterus is not their property. I cant believe they’re trying to do this.” Thank god for teen blitheness, which, when disturbed, sparks unfakeable energy.

But if such nutty politics is a good recruiting seargeant, it also wears down older activists. “So sick of it,” the spokeswoman for Planned Parenthood Colorado had told me last time I was here — prior to contesting it on the ballot, they had spent years trying to keep it off altogether, with campaigns pointing out the full ramifications of such a measure.

The weariness is in part because the strong rejection of the measure previously might create complacency among a wider circle of progressive voters — and the current form of the amendment may be far more plausible to a wider circle of voters. Where previous versions actually spoke of protecting the “zygote”, the current version talks of mother and unborn child protection, and links to a campaign by a woman who survived an accident with a culpable driver but miscarried her eight-month pregnancy. She wants the driver prosecuted for homicide of the child she would have had, and it is around this powerful and emotive story that the current campaign has been wrapped.

The group running it, Personhood USA, was expelled from National Right to Live, easier this year, for being too extreme. Presumably, any personhood amendment would clash with the US constitution and be struck down. But that takes time, and were it to get up, it could be used to close down any and all clinics offering such services, creating years of disruption. And these days, with this Supreme Court, you never know.

Hitherto, the issue has floated free of the wider campaigns, and progressives have run a determined but focused response, treating it as an extreme aberration to be seen off. This time around however, the personhood amendment has entwined itself around the entire election in Colorado, both the tight Senate race between Democratic incumbent Mark Udall, and Tea Partyish opponent Cory Gardner, and the fight for the key sixth district. Udall is a two-term Senator and a scion of an old midwest progressive political dynasty. Gardner is a Colorado Congressman who has been part of the Koch brothers inner circle, is receiving millions in funding through their “Americans for prosperity”, and is listed as the 10th-most right wing figure of the 435 members of the House of Reps. Udall should be beating him easily — he has a lot of money behind him too — but he is struggling and possibly running a few points behind.

Having shaped pretty much his entire campaign around the “personhood amendment” hoping to get a crucial edge in a gender split vote, Udall had been blindsided by the state’s leading paper The Denver Post, which has endorsed Gardner — a move akin to Fairfax endorsing Cory Bernardi. The Post claims to have been dismayed by Udall’s exclusive focus on the personhood vote, which it says is a side issue — because what could be more peripheral than the definition of what a person is — and has thus endorsed Gardner as a fresh voice for Colorado blah blah. A more cynical take would be that a struggling newspaper is desperate for a bit of publicity — and, in standard.practice, has endorsed the likely winner of a low-turnout election to claim a kingmaker status.

Well, they may get away with it — every Democrat is taking heat for the perceived diffidence and poor decisions of Barack Obama in recent months, and that may be the deciding factor. But midterm elections are notoriously hard to predict, and progressives have a better ground game — I’ve seen three vote Udall and “no to 67” groups in the central Denver grid and none of the opposition. This state is the front line of the culture wars here. Every time you curse the election of Abbott, spare a thought, and imagine what it would be like to have to fight these basic battles toe-to-toe every frikkin two years, for no reward other than holding the line.

The “no to 67” footsoldiers are American progressive politics at its best — tireless, relentless, endlessly committed. More power to the hand that holds the clipboard.