Frustrated Philadelphia voters should seize an opportunity today to tell investigators about problems they experienced at the polls during last fall's presidential election. A record 27,355 had to vote by provisional paper ballot on Election Day.

An investigative team appointed by Mayor Nutter is one of three groups hoping to find out the facts behind the widespread missteps and make sure future elections are not similarly disrupted. Voters' testimony to the team at a City Hall hearing this afternoon may help explain why the birthplace of modern democracy had so much trouble running an election. The public deserves to know what happened and why.

On Nov. 6, many voters showed up at polling places only to discover that their names were not in the voting books, forcing them to vote by provisional ballot. The problem with such ballots is that they are typically not counted on Election Day, so the votes they represent really aren't part of the great civic exercise until well after the election. Worse, some paper ballots are thrown out due to minor errors by voters or poll workers.

The city commissioners, the elected officials who supervise Philadelphia's elections, also launched a probe soon after the election, as did the city controller. The commissioners found that about 8,000 of the provisional voters were not actually registered to vote. Many others showed up at the wrong polling place - probably because about a third of the city's polling locations have been moved since 2008. But more than 5,000 properly registered voters who showed up at the right polling place had to vote by provisional ballot due to a problem with data from the Pennsylvania Department of State.

Unfortunately, the city commissioners are not participating in Nutter's probe. Al Schmidt, the only Republican commissioner, has complained that five of the six members of the mayor's investigative team work for Nutter, that the team has no Republican representation, and that it is short on election experience.

While Schmidt may have some legitimate concerns, he and the two Democratic commissioners should be at the forefront of those calling for answers and working with fact-finders. The commissioners should also understand that calls to put an end to their antique operation are only strengthened when they fail to cooperate with legitimate investigations of election problems.

For those who want to participate in the probe - and every concerned voter should - the first hearing is set to start at 4:30 p.m. today in the Mayor's Reception Room, on the second floor of City Hall. A second hearing is scheduled for 4:30 p.m. on Feb. 28 at Bright Hope Baptist Church, 1601 N. 12th St.

Let's hope the testimony of voters and others helps clear up the confusion that plagued the presidential election so the system can be fixed before the May 21 primary.