The race for the Democratic nomination for mayor of Pittsburgh keeps evolving in unexpected ways.
It was unusual when the primary election season began with an incumbent, Luke Ravenstahl, seeking re-election but nonetheless facing two well-known and formidable challengers from his own party -- city Councilman Bill Peduto and Controller Michael Lamb.
It took a more surprising turn when Mr. Ravenstahl stepped out just before the filing deadline, triggering a rush for petitions by other leading city Democrats -- former state Auditor General Jack Wagner, city Council President Darlene Harris, state Rep. Jake Wheatley and state Sen. Jim Ferlo -- along with newcomer A.J. Richardson.
The potential seven-member field would have offered city Democrats plenty of choices. But for some voters it would have been a dizzying array of candidates to compare and it would have threatened to deliver a nominee with a relatively small plurality of party support.
During the past week, though, the list suddenly contracted, with announcements by Mr. Ferlo, Mrs. Harris and Mr. Lamb that they have halted their campaigns. Mr. Lamb's withdrawal Monday was particularly significant because he had captured the endorsement of the city Democratic committee, which now must determine how to proceed.
The narrowed field is good news for voters, because it will make it easier to learn the strengths and weaknesses of each candidate and discern differences among the remaining four Democrats as the May 21 primary approaches.