PITTSBURGH — A popular city councilman has filed paperwork to raise funds for a run in the Democratic primary next year against Pittsburgh Mayor Luke Ravenstahl.

And Councilman Bill Peduto has picked up a powerful political ally in the process.

Even before Peduto announced the filing today, Allegheny County Executive Rich Fitzgerald announced he wanted to be the first to contribute to Peduto’s campaign.

Fitzgerald, also a Democrat, was elected in November.

Peduto spokesman Eric Hagarty says the councilman won’t formally announce his candidacy until after the November general election.

Peduto has run for mayor twice before. He lost in 2005 to Bob O’Connor who died in office and was replaced by Ravenstahl, who was city council president at the time.

Peduto also ran briefly in 2007, but dropped out before the primary.