Tension is building between Vancouver mayoral hopefuls as they fight to be their respective parties' chosen candidate in the city's November municipal election.

Non-Partisan Association councillor Peter Ladner faced incumbent mayor Sam Sullivan on a local talk radio show on Thursday to debate his desire to be the city's new mayor, as Vision Vancouver mayoral candidates gathered for a debate with party members later that evening.

NPA party members will vote between Ladner and Sullivan on Sunday, and Vision Vancouver members vote between Raymond Louie, Gregor Robertson and Allan De Genova on June 15th.

The NPA debate showed the party's race is uglier than the seemingly jovial nature of the Vision Vancouver candidates, as Ladner insisted his popularity has grown and Sullivan's has waned.

"His popularity has peaked," Ladner said. "Mine is growing."

Sullivan responded by saying he has heard that before and such criticisms never stopped him.

"I've heard that over and over again, 'Sam can't, Sam can't win, can't do this or do that,'" Sullivan said. "You know what? I've heard that all my life."

The bitterness amongst the NPA party is one of the reasons many supporters will likely throw their support to Vision Vancouver, according to civic political analyst and ctvbc.ca blogger Alex Tsakumis.

"What you're going to see is 50 per cent of the NPA's base walk the other direction regardless of who wins," he said.

Vision candidates Louie, Robertson and De Genova complimented each other amid laughter during their debate, and cracked jokes about the opposition party.

"May the best man win," said Robertson.

"Certainly it's entertaining for us to watch the other side implode," said Louie, to much laughter from the crowd.

With a report from CTV British Columbia's Shannon Paterson