HARRISBURG - Pennsylvania voters should expect to be asked for photo identification at polling places in Tuesday's primary election, but those without it won't be barred from voting.

The statewide balloting is being used for a test run of the new law that - starting in the Nov. 6 general election - will require Pennsylvanians to show a photo ID that meets state guidelines every time they vote. The goal is to educate voters and identify problems so officials can better prepare for the much larger turnout anticipated in November.

The law Gov. Corbett signed last month following an intensely partisan debate put Pennsylvania among a handful of states with the strictest voter-ID requirements amid ongoing GOP efforts in legislatures across the country to toughen such laws.

Republicans who advocated the law portray it as an effort to curb voter fraud, although Democratic critics charge that there's no evidence of such fraud. They have argued that the law is a thinly veiled effort to suppress the vote for President Obama in a key battleground state in the fall election and that it discriminates against elderly, poor and minority voters.

The American Civil Liberties Union has vowed to challenge the Pennsylvania law in court.

In the primary, poll workers will ask voters for an acceptable form of ID - a Pennsylvania driver's license, for example - but allow registered voters to cast ballots whether or not they have it. Leaflets describing the requirement and how to comply will be handed out.

The law allows Pennsylvania driver's licenses to be used as an ID for voting purposes up to one year past the expiration date, but it requires all other photo IDs to contain a future expiration date.

In the general election, voters who do not have proper identification will be allowed to cast provisional ballots that will be set aside and counted only if they provide a valid ID to county election officials within six days. They also can apply for a free photo-identification card through PennDOT.