After weeks of backroom negotiations, the mayors of Vancouver and Surrey have wrested control of the regional mayors' council ahead of a contentious vote this spring on a proposed "congestion" tax to fund transportation.

Vancouver Mayor Gregor Robertson bumped out incumbent chairman Richard Walton for the top spot Thursday, saying there needs to be new leadership on the mayors' council to secure a Yes vote in the upcoming plebiscite.

The plebiscite, ordered by the provincial government, will ask residents to support a 0.5-per-cent provincial sales tax increase, dubbed a "congestion improvement tax," to help fund a $7.5-billion wish list of projects that include a Vancouver subway and light rail for Surrey over 10 years. The plan also requires provincial and federal funding.

"This is about ramping up our campaign and making sure we get strong support," Robertson said. "I felt it was important to ensure Vancouver was represented as well as bring my campaign expertise to the region."

Robertson was nominated by Surrey Mayor Linda Hepner, who beat out Delta Mayor Lois Jackson for vice-chair.

The vote was weighted, which meant Vancouver and Surrey — the region's biggest cities by population — had significantly more clout than the smaller municipalities.

Port Coquitlam Mayor Greg Moore, who asked for the weighted vote, said it will be up to all mayors to ensure the plebiscite is successful, but noted part of the strategy going forward is having a strong representative from both sides of the Fraser River — especially from B.C.'s biggest cities — to lead the campaign. Surrey is expected to have a larger population than Vancouver by 2040, which sets the timeline for the mayors' council transportation vision.

"There are large populations there and we need those mayors to play a prominent role to get the vote to pass," Moore said. "They will provide a strong incentive to get their residents to vote yes.

"All of us agree there is nothing more important going forward than winning this transportation plan."

Both Walton and Jackson said they will continue to work with Robertson and Hepner to push for a Yes vote, although Jackson was worried the big-city mayors' plates may be too full. She noted Hepner, who was just elected mayor in November, is dealing with a rash of crime in her city.

"Once you put Vancouver and Surrey together, they've got their votes and the rest of us don't have any power," said Jackson, who had been nominated by Maple Ridge Mayor Nicole Read, one of three mayors to oppose the plebiscite. "I just hope they both have a lot of time because I know how much time Richard was spending on it."

Walton, who had chaired the mayors' council for the past four years and was vice-chair before that, said it will take a significant amount of work to organize the education campaign as well as work with the provincial and federal governments to secure additional funding for the mayors' council plan. The Yes campaign is expected to cost as much as $4 million, most of which will likely come form TransLink coffers and focus on educating residents about what they will get in the plan.