Gerry Shih

Board of Supervisors President David Chiu (left) would see his mayoral candidacy weakened if interim Mayor Ed Lee (right) enters the race.

With interim Mayor Ed Lee moving closer to announcing his candidacy for a full term, a sense of betrayal and fear is settling over the field of mayoral candidates, most of whom would be overshadowed by the popular incumbent.

Most vulnerable is Board of Supervisors President David Chiu. In one of the race’s ironies, the man who Lee’s opponents once criticized for his instrumental role in installing Lee as interim mayor is now the contender perhaps most threatened by his candidacy.

For several months, Chiu has tried repeatedly to gauge the mayor’s interest in running in private conversations. He knew that a Lee campaign would siphon away money and support out of Chinatown, the political base that Chiu depended on to win his seat on the Board of Supervisors in 2008.

Now, after months of denying that he had any interest in running, Lee appears close to making a 180-degree turn, signaling over the past week that he is considering entering the race, possibly as soon as Monday.

Thursday, Chiu said there had been an “absolutely clear understanding” in January when he chose to back Lee for the interim job that Lee would not run.

“The mayor has repeatedly said, publicly and privately, that he was not going to run,” Chiu told reporters at City Hall. “We hope that he’d be a man of his word and a man of integrity.”

People close to the Chiu camp say Lee had promised he would stay out of the race as recently as two weeks ago. His apparent reversal has sent shockwaves through Chiu’s campaign.

But Bevan Dufty, another candidate who was instrumental in elevating Lee to Room 200 in his final days on the board, said he had “no regrets.”

Lee “said to me directly that he wouldn’t run,” Dufty said. “But I entered this race knowing that there would be lots of twists and turns. In politics people have to do what people have to do.”

Another candidate, Supervisor John Avalos sought to associate Lee with his primary political backers, former Mayor Willie Brown and Rose Pak, who Avalos called “the establishment.” Avalos said he would present himself as a “fresh face.”

“Mayor Lee now is clearly showing that for the establishment there is a lot at stake,” he said. “For candidates like myself, we show a clear distinction, we offer independence and we offer a grassroots approach to government that heretofore has been untried in Room 200 in City Hall.”

Avalos warned that Lee’s record would be scrutinized in the coming weeks in a competitive campaign season.

“If he jumps in, we’ll consider him as a candidate in light of his record,” Avalos said. “We’re going to find out what he’s about, who’s backing him, who he’s going to work for.”

The campaign for Michela Alioto-Pier, another supervisor who lobbied for Lee during the succession skirmishes last January, did not respond to a request for comment.

Several candidates, including Joanna Rees, the venture capitalist, also struck a defiant note.

“If he wants to go back on his word and get into the race I welcome him,” said Rees. “I’ve been running against nine City Hall insiders and this will just make it 10.”

For his part, Chiu has maintained a veneer of unruffled optimism as he touts solid fundraising totals for the first half of the year.

On Thursday, as his campaign workers submitted a stack of 14,000 voter signatures to the Department of Elections, Chiu smiled for the cameras, adding that he number of signatures demonstrated “tremendous campaign momentum.”

Chiu sidestepped a question about Lee’s threat but acknowledged that he would shake up the race as soon as he announced.

“Any major elected official jumping in is going to have an impact,” he said.

When a local photographer pointed out that the public never elected Lee, Chiu paused momentarily.

“That’s right,” Chiu said. “He was appointed by the Board of Supervisors to be our interim mayor.”