HARRISBURG — Confusion over Pennsylvania’s new voter-identification law is likely to cause chaos at many polling places in Philadelphia, including longer-than-usual lines and shorter tempers as more voters are forced to choose between casting a provisional ballot and not being able to vote, a city elections official said Wednesday.

“I’m anticipating a mess on Election Day,” deputy city commissioner Jorge Santana testified at a Commonwealth Court hearing on whether the law should take effect as scheduled on Nov. 6. “I anticipate a lot of problems, a lot of tension, a lot of stress on the voters.”

Wednesday marked the sixth and final day of testimony in the hearing on a lawsuit seeking to block the law as a first step toward a broader challenge on its constitutionality.

Closing arguments are scheduled for today. Judge Robert Simpson has said he hopes to issue a ruling by the week of Aug. 13.

The case has ignited a fierce debate over voting rights in this swing state that could play a potentially crucial role in the presidential race.

Republicans in the Legislature passed the bill earlier this year without a single Democratic vote. Democrats charge the law is a political scheme to suppress voting by minorities, senior citizens and other groups in an effort to give GOP nominee-apparent Mitt Romney an edge over Democratic incumbent Barack Obama, who carried the state in 2008.

The new requirement that all voters produce a valid photo ID requirement is a sharp departure from current law, which requires identification only for people voting in a polling place for the first time and allows non-photo documents such as a utility bill.

The Philadelphia City Commission, which runs elections in the state’s largest city, is working with community groups to educate voters about the law, but state rule changes aimed at making easier for voters to get IDs have complicated that training, Santana said. The commission filed a brief supporting the plaintiffs in the lawsuit.

Voters who show up at the polls without a valid ID — a PennDOT-issued driver’s license or non-driver ID or any of several alternatives — may cast a provisional ballot but have to provide a proper ID to local election officials within six days for their votes to count.