PITTSBURGH—Psst! Pittsburgh City Councilman Bill Peduto is running for mayor.

Peduto "leaked" the news via a press release Thursday urging friends and the media to attend his holiday party.

The announcement was headlined "Councilman Bill Peduto To Make Big Announcement Tonight." It said that "hundreds of supporters will be gathering" to "hear a special announcement." Then the release states: "It is widely expected that Councilman Peduto will officially enter the race for mayor of Pittsburgh at this event."

Matt Merriman-Preston, the media contact listed on the release, said, "I can't confirm that for the record," when he was asked if Peduto would be making his third run for mayor.

"I haven't read his speech yet. But it's been about the worst-kept secret that he's making the announcement at some point," said Merriman-Preston, whose email address contains the domain name billpeduto.com.

The related website has a large blue-and-yellow sign that reads, "Run Bill Run" above big red panic-button-style links seeking donations and volunteers. The site is marked "Paid for by People for Peduto."

Peduto in September filed the paperwork necessary to raise funds under that name to run in next year's Democratic primary against Pittsburgh Mayor Luke Ravenstahl.

Peduto lost in the 2005 Democratic primary to Bob O'Connor, who was elected that November but died in office the following year. Ravenstahl succeeded O'Connor because he was city council president at the time.

Peduto also ran briefly in 2007, but dropped out of the special election that Ravenstahl eventually won to serve the rest of O'Connor's term after polls showed Ravenstahl was the overwhelming favorite. Ravenstahl then won a full, four-year term in 2009.

City Controller Michael Lamb also plans to run in the May primary. Although he's not made a formal announcement, Lamb told the Pittsburgh Post-Gazette earlier this month: "I have every intention of running. We are organizing, raising money, putting the team together."