Opposition Leader Bill Shorten has defended committing $200 million for the next stage of Canberra's light rail before the business case for the project has been finalised, saying the ACT deserved its "fair share" of infrastructure funding.
Liberal Senator Zed Seselja has also refused to rule in or out similar funding from a re-elected Coalition government.
The money for light rail from Civic to Woden would be included in Labor's first budget if it won government in the May election, Mr Shorten announced on Tuesday.
Speaking at the Alinga Street terminal after catching a tram from Dickson into Civic, Mr Shorten said he wanted to roll the stage one workforce "seamlessly" into stage two.
"This is the way public infrastructure should be built in Australia, moving in well-planned stages, keeping a pipeline of work for Australia’s construction workforce and subbies, the backbone of Australia," Mr Shorten said.
But uncertainty over the route has led to a delay in the finalisation of the business case.
Asked why Labor had committed this money without having seen this analysis, Mr Shorten said he wanted Canberra to get a "fair share of our expenditure".
"Of course there’s got to be a business case but I think the work that’s already been done combined with the business case which will come, I think it’s important we keep room in our budgets in the future," Mr Shorten said.
"People in the greater Canberra-Queanbeyan region, they pay their taxes, they've got a right to see some of it reinvested in their region. That’s what we’re doing."
He also said: "No town, no city ever goes backwards having light rail and trams."
“Can I tell you about the cities in the world who’ve had trams and ripped them up? They want them back. I’m a Melburnian, we’ve had them for 130, 140 years and we wouldn’t give up our trams for all the tea in China," Mr Shorten said.
Chief Minister Andrew Barr said the funding was a "strong signal" a federal Labor government would help smooth through the approval of the project, which must be endorsed by both houses of parliament.
He said it was a "welcome thing" to see a prospective federal government interested in Canberra and not" referring to it as a bubble".
"I don’t think there has been an announcement on this scale for this city for decades," Mr Barr said.
Previous estimates of the cost of light rail to Woden have been $1.3 billion-$1.6 billion although Mr Barr said it would now be "premature" to put a price tag on the project.
"Everything has changed now as a result of this announcement," Mr Barr said.
While a State Circle alignment was "in front at the moment in terms of the relative ease of the planning process", questions around how many people could be serviced and where stops were located would determine the final alignment.
Asked whether the ACT could afford another stage of light rail, Mr Barr said the territory had a "very robust balance sheet".
“The fundamental point remains this city is adding 10,000 new residents every year, [and] that one in five jobs are in the Parliamentary Triangle," Mr Barr said.
Senator Seselja would not rule in or out making a similar commitment, but suggested Mr Shorten was increasing taxes to pay for it.
"Canberrans will be paying for this commitment by Federal Labor, with Labor's retiree tax, their housing tax, and their tax hits on small business," Senator Seselja said.
The ACT Opposition's transport spokeswoman Candice Burch said the territory government must release a business case as soon as possible "so that Canberrans have full transparency of this proposed project".
“It is important we get this right before potentially committing billions of dollars to light rail from Civic to Woden. Canberrans deserve to know whether this is the best route for stage two,” Ms Burch said.