Both Singer and the other Democratic candidate, one-term incumbent Anthony Clark, rode the party's 6-1 registration edge to easy victories, leaving Democrats in control of the city election machinery.
Schmidt held his own on Duda's home turf in Northeast Philadelphia while outpolling Duda in neighborhoods like Center City, University City, and Northwest Philadelphia, where some liberal groups paired Schmidt and Singer on a slate to bring change to the commissioners' office.
Schmidt now holds the swing vote in determining whether Clark or Singer becomes chairman of the agency to replace 78-year-old Marge Tartaglione, the combative great-grandmother who has held the reins of the city election machinery for most of the last 36 years.
Caught in several political crosscurrents, Tartaglione was displaced by Singer, a former Haverford College professor, in the Democratic primary last May.
While considered likely to back Singer, Schmidt said Tuesday night that he remained uncommitted.
"It's the most important vote I'll cast," Schmidt said. "I want to sit down with both of them and hear about their plans for reforming the office."
He said his priorities included putting more information onto the commissioners' website, making it easier for people "to get involved in the civic life of the city," and "making sure the office is a model of integrity, so people have confidence that elections in our city are fair."
"Every election there are issues of voter intimidation and improper electioneering, and it keeps happening over and over again, with the office most responsible not doing anything about it," Schmidt said, repeating a campaign theme.
Schmidt, 40, has been a leader of an organizing effort funded by the state Republican Party to recruit more GOP committeemen and ward leaders inside Philadelphia.