HONOLULU -- An opponent came forward to challenge Mayor Mufi Hannemann for re-election on Tuesday.

He is a long-time rail transit critic and an engineering professor at the University of Hawaii.

Panos Prevedouros is a traffic engineering specialist who said if he is elected mayor, he would not only kill rail transit, he would also improve traffic, trash, sewage and conditions on Oahu's roads and city parks. He is challenging the mayor who's running for his second term.

Several dozen people, many of them active Stop Rail Now volunteers, gathered in front of City Hall to support Prevedouros.

"We need a mayor who's back in the days of Mayor Wilson's days, who's a nuts and bolts engineer, who will take care of the problems that face our citizens on this island today," Michael Lilly said.

"We can prevail in this battle of Panos versus Goliath," Mike Palcic said.

Prevedouros said Honolulu needs his expertise.

"It has a large number of infrastructure problems and the most important person to address this infrastructure problems is an engineer and preferably a civil engineer," he said.

The engineer said he is confident that rail opponents will gather enough signatures to force a vote on rail transit, which he said will bankrupt the city and will not solve traffic problems.

The mayor said while Prevedouros says he plans to fix parks and other city problems, he said his challenger is clearly entering the race for one reason.

"It was supposed to be Cliff Slater. He didn't want to run. It was supposed to be Charles Djou. He didn't want to run. So Panos wants to run. That's fine. Let's not, talk straight, OK. Let's say the real reason why they're running, this is all about stopping rail," Hannemann said.

Hannemann called Prevedouros a one-issue candidate who opposed rail transit here for 17 years.

"That's entirely untrue. I think the current administration is a single-project administration," Prevedouros said.

"That's preposterous, look at the record. The record is very clear. We have been doing things that haven't been done for years," Hannemann said.

Prevedouros plans to take a leave without pay from his 18-year career as a UH engineering professor. The timing is difficult because his fiance Katie O'Donnell is pregnant and due at the end of September, just after primary Election Day.

Hannemann has more than $2 million in his campaign war chest.

Prevedouros is starting out with no campaign funds. He said his will be a campaign about people and volunteers rather than money.