Three City Council members are asking that all council members and Mayor Mufi Hannemann refuse campaign donations from companies that may bid to provide vehicles for Honolulu's planned commuter rail system.

The City Council is expected to decide April 16 which technology — steel wheel, rubber tire, monorail or magnetic levitation — should be used for the planned $3.7 billion rail line linking East Kapolei to Ala Moana Center.

So far, vendors from Japan, Europe, Canada and the United States have expressed an interest in bidding on the city's estimated $230 million vehicle contract.

Council members Donovan Dela Cruz, Charles Djou and Ann Kobayashi are asking that elected city officials decline any political donations from 10 rail technology firms that have expressed interest in providing the vehicles for the mass transit system. The voluntary pledge also asks that officials return any such donations already received.

"I'm not accusing the mayor nor any of my colleagues of any sort of wrongdoing," said Djou. "If none of my colleagues or the mayor are engaging in wrong behavior, there really should be no problem in signing this petition."

The three signatories hope other elected officials will sign the petition prior to the April 16 rail technology vote.

"This is disingenuous political grandstanding," said Hannemann's spokesman, Bill Brennan, in an e-mail response yesterday. "Mayor Hannemann is ethically aboveboard and cannot be bought for a campaign contribution. He does not and will not accept any illegal campaign donations."

A city-appointed expert panel in February recommended Honolulu stick with reliable, nonproprietary, steel-wheel technology. However, some council members want to consider the more modern, proprietary alternatives of rubber-tired vehicles on concrete, monorail and magnetically levitated trains. Hannemann wants the council to select steel-wheel train technology.

Hannemann plans to break ground on the system late next year with limited service starting in 2012.