Transport spokesman Alistair Coe is set to move a motion calling for a delay in the $800 million contracts, the latest pitch in a heated debate about the project's cost and opposition plans to cancel contracts if it wins government.

On current plans, the government and a private consortium partner will sign contracts for construction and operation of line linking the city and Gungahlin in the first half of 2016, ahead of the October 15 poll.

Weeks after welcoming the Victorian Labor government's decision to pay $339 million to cancel a controversial road tunnel project, Mr Coe said the delay would show respect to ACT voters and avoid the need for a large compensation pay out.

"If the government is going to embark on the biggest ever capital works project in the history of the ACT government, I think there is an obligation to seek the support of the ACT community and the best way to do that is of course at an election," he said.

"It would seem to me the prudent and responsible thing to do is to put the project on hold and genuinely seek the support of the ACT community."

Mr Coe's motion will be defeated by government members with the support of Greens Minister Shane Rattenbury.

He will argue ACT Labor's only light rail commitment at the 2012 election was for $30 million in funding for design and engineering studies from the 2012 election.

Costing documents provided to the ACT Treasury by former chief minister Katy Gallagher in September 2012 estimated delivery costs for the project would be $614 million. The cost of construction through a large scale public private partnership was separate to the election commitment.

Ms Gallagher's governance agreement with Mr Rattenbury, signed after the election, included the establishment of the Capital Metro agency and a "target date" for the laying of tracks commencing in 2016.

In calling for a delay, Mr Coe cited the scale, cost and "widespread opposition" to light rail.

"I don't discount the fact there are some people who support the project but there is of course a very vocal component of our community who are fiercely opposed to this," he said.

"I would say it is a sizeable chunk of Canberra's population."

Mr Coe's plans to cancel contracts after the election has attracted criticism from the government and lobby groups including Infrastructure Partnerships Australia.

He was at odds with Prime Minister Tony Abbott over the Victorian government's decision, which came after the former Coalition government signed contracts for the East West Link project two months before voters went to the polls.

Mr Coe acknowledged speculation about a light rail line to Canberra Airport as part of a possible second stage could make the project more popular.

"We will decide whether any infrastructure project has merit based on the return it will give to the community," he said.

"The sheer fact that the government has another pipe dream to extend like rail to another destination is not good enough."

Last month Capital Metro Minister Simon Corbell released one of two expert reviews of the project's final business case, which found it was