By Cherri Gregg

PHILADELPHIA (CBS) – The Pennsylvania department of state predicted earlier this year that only 90,000 Pennsylvania voters were without a PennDOT photo ID. But figures released on Tuesday show they missed the mark by the hundreds of thousands.

“We used the best information we had at the time to make the best estimate we could.”

Spokesman Ron Ruman says, last fall, legislators asked the Department of State to quickly estimate the number of Pennsylvania voters who would need a PennDOT photo ID.

“We were asked to provide that information in a very short period of time as the bill was moving through the legislature.”

READ: Many Pa. Voters Don’t Have Proper Photo ID

He says the Department took a day and a half to compare US Census data to PennDOT records. The newest analysis took about two months and compared PennDOT records to voter registration rolls.

ACLU Legal Director Vic Walczalk represents 10 plaintiffs in a suit to block the voter ID law and says they’ll use the numbers to bolster the case.

“We’ve got enough now to be able to defeat this law.”

The trial to decide the fate of the voter ID law is scheduled to begin on July 25.