Under the leadership of Alex White, fresh from the 2014 Victorian election, the peak body Unions ACT is adopting sophisticated, targeted campaign techniques that sway voters by using firefighters, nurses and paramedics to win them over.

The technique is credited with ousting one-term Liberal governments in Victoria in 2014 and Queensland in 2015. It is borrowed from American politics, where pledges are used to make voters feel both committed and obliged to a cause.

The We Are Union campaign is targeting four of Canberra's five electorates, assuming the inner-city seat is not in play. Each electorate will elect five politicians. Mr White assumes two Labor and two Liberal for each, with the fifth seat in each electorate determining who forms government in October. The Greens are assumed to have the fifth seat in the inner-city seat tied up, leaving four electorates where the final candidate is undecided and crucial – Tuggeranong, Woden-Weston, Belconnen and Gungahlin.

Unions ACT has already identified 8000 people across the four electorates who it thinks are persuadable – they are union members or people who have shown interest in previous campaigns or issues. It has discounted the rusted-on Labor and Liberal voters, leaving a core of about 2000-2200 voters in each electorate. It believes that swaying just 400 votes will be enough to get the fifth candidate elected, since the key to winning the fifth seat is getting enough first preferences to stay in the count.

Volunteers have called the voters already to establish their key issue. Starting on May 1, the voters will be visited by Mr White's army of almost 900 volunteers, one of whom will be a worker in the area of interest – such as a nurse, teacher, tradie, firefighter or paramedic, dressed in clothes that clearly identify their profession. At that meeting voters are asked to sign and date a pledge, adding a sentence in their own writing about why it is important to them.

Crucially, the pledge will be mailed back to them two weeks before the election, along with a score card comparing the major parties on the key issue. They will also get reminder calls to vote.

Mr White said he volunteered in the Victorian campaign, knocking on hundreds of doors and no one turned him away, given he was accompanied by a nurse, paramedic, or firefighter. It was bringing back an old style of democracy with "neighbours talking to neighbours", rather than big donors and expensive television advertising campaigns.

"It's radical because it's so democratic," he said.

Research shows that asking people to sign a pledge makes it more likely they will follow through on election day, because it impacts on how people feel about and see themselves and because they want to keep the promise. But Mr White rejected the suggestion that the visit or the pledge were manipulative.

Everyone being targeted was a union member or interested in union issues, and they were simply being visited by a worker in an area of interest to them. They were not being forced to open the door, nor to sign the pledge, and nor were they being told how to vote, Mr White said, insisting the campaign was not about re-electing the Labor Party but about persuading all the parties to adopt the union's issues.

Pledges worked, unlike letter boxing or non-targeted doorknocking, he said, predicting the campaign would change the outcome of the election.

"We're being completely open and honest about who we are. We're wearing T-shirts saying we are union. We're only talking to union members and union supporters and we're being completely open and transparent about what we're doing, who we're talking to and who we are."