Requiring voters to have a photo ID to cast their vote lowers the turnout off voters, concluded a nonpartisan watchdog from Congress in a huge report released on Wednesday. The reports said that young, newly registered and black voters were the most likely to stay away.

In contrast, Government Accountability Office researchers said they could not determine how much the quantity of voter fraud, the problem that voter DI legislation is meant to combat, was going up.

The new study, which comes less than one month prior to voters going to the polls for midterm elections, is boosting the opponents of the voter ID measures who say it is time to end the laws that curtail a complete pool of voters.

An independent Senator from Vermont, Bernard Sanders said it must be made easier not harder for working class and poor people to cast their vote and participate in the country’s political process.

Sanders said the state laws are not actually intended to lower fraud, but to discourage voting.

The extensive study done by GAO looked at existing voter turnout reports, which showed a mix of results, but also they did a new study on voter turnout in Tennessee and Kansas, both of which instituted laws pertaining to voter IDs prior to the election in 2012.

Investigators said the turnout of voters in both Tennessee and Kansas fell off more than in other state that are similar that did not impose requirements of new IDs

Laws for voter ID have become a political topic that has been fiercely debated over recent years, with the ID law in Wisconsin currently being challenged in court. The U.S. Supreme Court is considering whether or not to block that law.

In 2008, justices upheld a photo ID law for Indiana finding the state had legitimate interests in deterring the voter fraud and in ensuring the election would be smooth, which outweighed the claims of opponents that elderly and minority voters lacked photo identification at rates far higher than the rest of the general population and would therefore be deterred for casting their vote.