SALEM, Ore. (AP) — A photo of Rep. David Wu wearing a tiger costume and other unusual revelations about his mental health are increasing pressure on the seven-term Oregon Democrat to step down.

But the lawmaker says he's not quitting even as an editorial in one of the state's largest newspapers and the state Republican chairman called for his resignation.

Wu said this week that it was "unprofessional and inappropriate" to send pictures of himself wearing a tiger costume to staff members while he was in the middle of a heated campaign last year. He also acknowledged taking two tablets of a pain killer that were given to him by an unnamed campaign donor.

"This was the only time that this has ever happened," the congressman said in a statement of the pain killer episode. "I recognize that my action showed poor judgment at the time, and I sincerely regret having put my staff in a difficult position."

Seven staff members resigned after the campaign following bizarre behavior that concerned his team at the end of the 2010 campaign. The Oregonian also reported that Wu's campaign was fined by state officials for failing to carry workers compensation

The Eugene Register Guard, Oregon's second-largest newspaper by circulation, published an editorial Wednesday calling for Wu's resignation "for lack of candor, not because of treatment."

"Wu should have been forthcoming about his medical treatment when it began," said the paper, which publishes outside Wu's district.

Another paper, the Daily Astorian from Clatsop County in Wu's district, planned to publish an editorial Thursday also suggesting that Wu should step down, saying the congressman has served the region well but "certainly Wu is becoming an embarrassment."

"He has a really important job, and the citizens of Oregon and the citizens of the congressional district deserve to have a congressman who's completely focused on serving them and being a great congressman," Oregon Republican Party Chairman Allen Alley said Wednesday.

Wu's spokesman said the congressman has no plans to resign and will seek re-election in 2012.

"It will be up to his constituents to decide whether he's proven himself," Dorey said.

Wu tried to confront the criticism in a network television interview on Tuesday, telling ABC's Good Morning America that he's being treated with counseling and medication and saying he has overcome any mental issues that occurred during a stressful midterm election.

Wu was unavailable Wednesday to comment, said his spokesman, Erik Dorey. The congressman will be in Portland this weekend and plans to speak with reporters then, Dorey said.

Wu's district is a Democratic stronghold that includes the west side of Portland and the city's technology-heavy eastern suburbs, including the global headquarters for Nike and a major factory for chipmaker Intel. It stretches northwest to the coast and south into Oregon's wine country.

Wu was a political newcomer when he was elected to Congress in 1998 as the first Chinese-American to serve in the U.S. House. He's maintained a centrist voting record but been a leading voice on human rights abuses in China, and he angered the high-tech firms in his district when he voted against normalizing trade relations with China.

Even as Wu faces pressure to quit, some of his top political supporters are sticking by him.

"We support David Wu because he's a strong supporter of working families," said Arthur Towers, political director for the Service Employees International Union in Oregon. "Clearly he's going through some personal health problems, and now is not the time to change our position."

Richard Schwarz, executive director of the American Federation of Teachers in Oregon, said Wu is entitled to seek medical care.

"We have no reason at this point to not support him," Schwarz said.

A special election would be held to fill out Wu's term if he were to step down.