Stage two of the planned Canberra light rail to Woden would be delayed or even scrapped entirely, if the Belco Party holds the balance of power in a hung ACT Assembly after Saturday's election.
The minor party, founded by former Liberal leader Bill Stefaniak, said the ditching of plans to send the light rail over Lake Burley Griffin would be a major condition of support for a major party to form a government, if a party does not get enough seats to govern in their own right.
Mr Stefaniak said the party would aim to have funds earmarked for the transport project redirected to other programs.
"This will also allow time to consider fully any business case there is for stage two and additional stages for light trail," Mr Stefaniak said.
"It will also allow for proper and full studies of just what are the best future transport options for all of Canberra."
The minor party said more than $1.9 billion would be saved, and called for whoever forms government to allow more conscience votes on issues.
"Any agreement with the Belco Party would require rules to ensure ministers, including the Chief Minister, actually see constituents. There are other conditions we would seek," Mr Stefaniak said.
Chair of the Public Transport Association of Canberra, Ryan Hemsley, said he was disappointed by the Belco Party's announcement.
"There is a non-zero chance that the Belco Party will be the kingmakers in the next Legislative Assembly," he said.
"If this is genuinely their policy on light rail stage two, then they should have been upfront and transparent about it.
"It's disappointing that they have instead chosen to announce it, then seemingly hide it, the day before the polls close and 60 per cent of the electorate had already voted."
Stage two of light rail, which Labor has committed to, would see tram routes built from Civic and onto the Woden town centre.
Approval on the final route, which would go through the parliamentary triangle, would be dependent on a sign off from the National Capital Authority.
The Canberra Liberals' transport spokeswoman Candice Burch said earlier in the election that the party would conduct a study to determine where the second stage would go, with some feedback suggesting Belconnen would be a better alternative.
However, the party's leader Alistair Coe said just days later the Liberals were committed to Woden being the next stop for the light rail and supported doing an independent assessment of the business case.