City Councilwoman Jannie L. Blackwell and City Commissioner Stephanie Singer were among 12 Philadelphia candidates whose nomination petitions were challenged Tuesday in Common Pleas Court.

The challenge against Singer, a Democrat, contends that she did not have enough valid signatures on her petitions. Singer said she gathered about 1,480 signatures and was certain she had more than the required 1,000 valid signatures to be placed on the primary ballot.

"When they can't beat you at the ballot box," she said, "they try to beat at the courthouse."

The challenge was filed on behalf of Daniel Bucher by Richard Hoy, a lawyer who described his client as a Philadelphian "who does not like to see improperly filed nominating petitions."

Hoy said he found numerous errors in the petitions, including wrong addresses listed for signers.

Blackwell could not be reached for comment, although a court source said her petitions had been challenged for being improperly notarized and lacking a proper statement of financial interest.

Singer and Blackwell will have an opportunity to defend their petitions in a court hearing.

Only one Democratic mayoral candidate - T. Milton Street Sr. - had his petitions challenged. The challenge against Street alleges he does not live in the city and was not registered as a Democrat.

Petitions for three Democratic candidates for City Council at-large - Lillian Ford, Billy Ivery, and Karen Gordon - were contested.

Election lawyer Charles Gibbs filed the challenges against Ford and Ivery, contending they lacked the proper number of valid signatures.

Adam Bonin, who filed the challenge against Gordon, could not be reached for comment.

Others whose petitions were challenged included: Larry King, Democratic candidate for sheriff; S. Archye Leacock, Democratic candidate for Ninth District Council seat; Tony D. King, Democratic candidate for the Third District Council seat; Greg Paulmier, Democratic candidate for the Eighth District Council seat; Sabriya Bilal, Democratic candidate for the Ninth District Council seat; and Dennis Lee, Democratic candidate for city commissioner.