WASHINGTON (AP) — A nonpartisan congressional study has found that stiffer state voter ID laws have damped election turnout, disproportionately affecting blacks and younger people.

The Government Accountability Office found that election turnout in Kansas and Tennessee — which tightened voter ID requirements — dropped more steeply than it did in four states that didn’t change their identification requirements.

The report found that in those two states, voter turnout was more sharply reduced among young people than among the middle-aged and among blacks than whites and others.

Young people and blacks generally tend to support Democratic candidates.

Republicans have said such laws are designed to reduce fraud.

The report was released less than four weeks from Election Day.