Australia's largest road toll operator Transurban says it is not interested in Victoria's proposed East West Link.
The State Government wants to get started on the tunnel next year.
The project, aimed at easing Melbourne's traffic gridlock, is worth up to $8 billion.
Transurban operates the State's CityLink toll road but says it is not interested in the East-West Link under the current funding model, in which the Government would receive the tolls.
The Chief executive Scott Charlton has told an investor briefing it may reconsider if an alternative funding approach is taken.
"If the government identifies and needs to look at alternative funding approaches we continue to be open to explore options with the government," he said.
"Currently the East West Link is an availability payment model and it is not consistent with our strategic approach or risk profile on how we would approach our traditional projects for Transurban."
But he said he would be keen to talk to the government about how it linked with the company's existing CityLink toll road.
Mr Charlton's investor briefing comes as the the Federal Opposition Leader Tony Abbott told reporters in Melbourne the project has merits, but admits he has not seen a business case.
"There are lots of things I haven't seen, and I know there is a business case for the East West Link," he said.
Mr Abbott has already pledged $1.5 billion if the Coalition wins office.
But he, and the Premier Denis Napthine, appear to be at odds over transport funding.
his views on funding the metro rail tunnel.
But Mr Abbott says it is not true.
"We will not be committing to the Metro Rail scheme, I've made that absolutely crystal clear," he said.
The Federal Government has seized on the divide.
The Federal Transport Minister Anthony Albanese says this suggests Mr Abbott is lazy when it comes to policy development.
"He's not interested in funding one cent for any public transport project," he said.
"What we've had here is either Denis Napthine verballing Tony Abbott, or Tony Abbott saying one thing to the Premier and another thing publicly."