I'll vote Green if you do: could pledges save politics?

Picture this. It's May 7th and you're heading to the polling station to cast your vote. You're fed up of Labour's dithering on key policy issues, you feel like the Tories are out of touch and Ukip are a bit ranty for your taste. What you'd really like to do is vote Green, but you're worried that, despite all the excitable talk of a "Green surge," nobody else is actually going to. In the end, feeling like a fraud, you put an "x" in the box next to whichever choice makes the most tactical sense in your constituency.

"I'll vote Green if you do" is a site set up to prevent this very scenario from happening. Jonathan May, a Green Party member and director of trade association the UK Crowd Funding Association, knew the power of what he calls the "pledge mechanic." Crowdfunding sites work on the principle that people are more likely to give money to a project if they can see that others are pledging to do so. They'll be secure in the knowledge that they aren't the only person supporting it, and—as crowd funding projects only happen once a minimum target is reached—they'll feel pressure to share it with their friends so that their pledge counts for something.

May reasoned that this could work for his party. The site, which May cobbled together on a dull train journey from Bristol to London, encourages users to "pledge" to vote Green. Others can see who has pledged, and can, crucially, find out how many in their constituency have done so.

It's a savvy idea. The Greens are booming at the moment; they recently overtook Ukip in terms of membership, with more than 44,000 members, up from around 27,000 in December. A YouGov poll this week put their support at 10 per cent—its highest ever rating for the party. But whether this support will translate into seats at the general election is questionable. Ostensible Green voters might chicken out and  vote tactically—in one recent poll for Times Red Box, for example, a third of people who said they would like the Greens to win said they would probably vote Labour in their constituency. Even if this many people do vote Green, our first past the post system—which Vernon Bogdanor slams in the latest issue of Prospect—might mean their support isn't sufficiently concentrated to hand them many seats. If enough people sign up to the pledge, it could help bolster Green voters' confidence and tip the balance in their favour.

So will it work? Tim Bale, professor of politics at London's Queen Mary University, reckons the site could potentially have either a positive or a negative effect on the Green vote. On the one hand, he says, someone looking at the site and thinking about voting Green might be buoyed up by the knowledge that hundreds of others are doing the same. On the other hand, he points out, "it might also make it obvious that it's not 20,000." In other words, those unsure that a vote for the Greens will count might have their doubts confirmed if they look at the site and don't see an enormous groundswell of support already registered.

A lot will depend on how quickly the site spreads. May tells me that he ended up releasing it by mistake; after he casually told a couple of friends it was up it spread and gathered around 2,000 signatures within two or three days, crashing his email server. After 13 days, almost 10,000 have pledged. If the site continues to build momentum, it may sweep excitable voters up with it. If it stalls, the opposite might happen.

Of course, a pledge in January won't always translate into a vote come May, but in the 1996 US Presidential election, the Democrats found that asking potential voters to sign "pledge cards"—an old-fashioned pen and paper equivalent—during the campaign made them significantly more likely to vote Democrat on polling day.  The Conservatives have set up a similar mechanism, suggesting they reckon the tactic could work, though a spokesperson was unable to confirm whether it was inspired by May's site or not.

As Bogdanor argues: "First past the post... serves the interests not of the voters but of the two major parties, of political insiders and the political class." Anything which allows voters to overcome the defeatism it inspires is likely to help solve our democratic deficit. I'll vote Green if you do might fail, but anyone interested in the health of British democracy should watch it closely over the coming weeks.