Laws that require voters to present identification at the polls reduced voter turnout in the 2008 and 2012 general elections, according to a report released Wednesday from the U.S. Government Accountability Office (GAO).

Further, voter ID laws decreased turnout to a greater degree among new, young, and African-American voters.

The GAO’s analysis looked at turnout in Kansas and Tennessee, which have voter ID laws, compared to four other states—Alabama, Arkansas, Delaware, and Maine.

Republicans have touted voter ID laws as necessary to prevent voter fraud.

However, the congressional watchdog states that “the studies GAO reviewed identified few instances of in-person voter fraud,” though it noted that there are challenges to gathering information needed to make such estimates.