Peter Ladner successfully challenged Mayor Sam Sullivan to become the Non-Partisan Association's mayoral candidate in November's civic election. (CBC)

Vancouver Mayor Sam Sullivan won't be running for re-election under the political banner of the Non-Partisan Association after losing to Coun. Peter Ladner in Sunday's nomination process.

Ladner received 1,066 votes of support to represent the ruling party in the mayoral race in November. Sullivan secured 986 votes.

NPA members cast ballots from 10 a.m. to 4 p.m. PT at a nomination convention held at a downtown hotel on Sunday.

"As I said many times, I'm doing this out of loyalty to the NPA because I think I can offer a better alternative and we can win in November," Ladner said during his victory speech.

Ladner was first elected to Vancouver city council in 2002 and re-elected in 2005.

Sullivan says he respects the democratic process and that the nomination vote was very close. (CBC)

Sullivan said Ladner did a good job campaigning and the race was close.

"I'm very philosophical about it. I think that I do my best. I offer what I have to give to the city and to the NPA," Sullivan told reporters.

"I'm very respectful of the democratic process. Peter Ladner did a very good job. He was very organized and I congratulate him for it."

Sullivan was elected to council in 1993 and served as a councillor for 12 years before being elected mayor in November 2005.

"I'm really honoured to continue to finish off my term and I will go on and do something else," Sullivan said.

The pair squared off in a debate in front of a small crowd at the convention before polls opened in the morning.

Sullivan talked about homelessness and crime, while Ladner's speech focused on making Vancouver a greener city and how it can compete on the global economic market.