An extension of the Millennium Line to the University of British Columbia would cost around $3 billion dollars, has no funding commitments and wouldn't be operational for nearly a decade..

But that hasn't stopped it from becoming an election issue.

With funding for the extension to Arbutus Street now secured and construction scheduled for 2020, Vancouver mayoral candidates have been asked whether they would support continuing the line all the way to UBC.

Such a move would bring relief to transit commuters: according to TransLink data, the four bus routes with the most overcrowding all travel to or from UBC, and the 99 B-Line has nearly double the amount of boardings (17.4 million in 2017) than the next most popular route.

Here's a summary of what the leading candidates have said.

Sylvester and Bremner: top priority

Independent candidate Shauna Sylvester and Yes Vancouver candidate Hector Bremner both said a UBC extension would be a key priority in their term, with hopes of working quickly so that construction wouldn't have to wait until the Arbutus extension is finished in 2025.

"While we have an alignment with [all three] governments, interests from the Musqueam and UBC contributing money, we want to unlock money quickly to get it built all in one phase," said Sylvester.

"That's always been part of the plan. It kind of fell off when Vancouver didn't demonstrate the type of leadership needed to get the Mayors' Council on side."

Bremner argued he would be more effective at getting an extension built quickly, because he would be more aggressive in pushing for rezoning and development that would allow the city to put a greater share of funds toward the project.

"The city will not be able to get the line unless we have a city plan that unlocks enough economic activity to pour back into transit investment," he said.

"Talking to people in Ottawa or Victoria is not going to get it built."

A slide from the presentation to UBC's board of governor's about the possible extension of the Millennium Line to the university's campus. (UBC)

Ken Sim: 'not at the top of our list'

Among mayoral candidates that have managed to get at least 10 per cent in recent polls, the NPA's Ken Sim was the most pessimistic about an extension.

"Right now, the line out to UBC, it's not at the top of our list," said Sim.

"It's not that I'm against the line. I'm just very pragmatic. These are the issues we have to address. Even if we do get funding, it's years in the future, and we have immediate congestion issues now and getting around our city, and that's what we should be focused on."

To support his point, Sim said ridership data from TransLink shows two-thirds of ridership from Commercial Drive on the 99 B-Line "falls off by the time you hit Arbutus."

When asked if Sim's information was correct, a TransLink spokesperson said that in Sept. 2017, 76 per cent of B-Line boardings happened between Commercial and Arbutus.

Stewart: "the thing I won't do is overpromise"

Trying to take a position in the middle is independent candidate Kennedy Stewart, who criticized Sim for his lukewarm embrace of an extension.

"If the mayor of Vancouver doesn't do it, it's not going to happen, and that's why Ken Sim has made such a big mistake," he said.

However, he also didn't want to commit to getting an extension done, because any agreement would be contingent on funding from other levels of government.

"The thing I won't do is overpromise. And that's what other candidates are doing. They're saying they will build it on our own. They're going to use city property taxes to build a SkyTrain. We can't do it. It has to be with federal and provincial governments and UBC as partners."

Fred Harding of Vancouver First, David Chen of ProVancouver and Wai Young of Coalition Vancouver have all said at all-candidate forums they support an eventual extension to UBC but have not highlighted the issue in their platforms.