A recent fundraising trip to Pittsburgh is again causing heartburn for the Democratic gubernatorial campaign of Mayor Mufi Hannemann.

Honolulu lawyer John McLaren asked the state Campaign Spending Commission yesterday to investigate the fundraiser, asserting in part that Hannemann’s signature on an official notice of the June 9 event did not appear authentic.

McLaren also has asked City Councilwoman Ann Kobayashi to look into the mayor’s travel expenses for the trip and the propriety of the fundraiser, which was organized by a former executive of a firm that is seeking a $230 million contract to build cars for a proposed rail project in Honolulu. McLaren previously filed a complaint about the city’s handling of rail project contracts.

Kobayashi, who in 2008 challenged Hannemann’s bid for a second term, said she would look into the assertions. She also is inquiring into Hannemann’s participation last year in a fundraiser in Denver, which she said occurred while he was supposed to be at a conference in Los Angeles that the Council had authorized him to attend.

"It’s just that there are all these discrepancies," she said.

Hannemann campaign spokeswoman Carolyn Tanaka, noting that the Campaign Spending Commission is investigating the Pittsburgh fundraiser, said there would be no comment.

The turn of events comes less than three months before Hannemann and former U.S. Rep. Neil Abercrombie square off for the Democratic gubernatorial nomination. The winner is likely to face Republican Lt. Gov. James "Duke" Aiona in November.