The U.S. Commission on Civil Rights urged Congress on Wednesday to update the landmark law that protects voter rights, finding in a new report that a 2013 Supreme Court decision helped lead to elections with voting measures in place that discriminate against minorities.

But opposition from Republican lawmakers has stalled legislation to change the Voting Rights Act of 1965 since the 5-4 decision in Shelby County v. Holder that struck down a key enforcement mechanism in the law. Current efforts appear stuck for the same reason.

“Today’s report reflects the reality that citizens in the United States, across many states, not limited only to some parts of the country, continue to suffer significant, and profoundly unequal, limitations on their ability to vote,” commission Chair Catherine Lhamon said in a news release. “That stark reality denigrates our democracy and diminishes our ideals.”

The Shelby County decision struck down Section 4 of the law, which required some states with a history of discriminatory voter laws to get pre-clearance from the Justice Department before implementing voting laws. That section created a formula for how states and jurisdictions should comply with the pre-clearance standard, which the conservative justices who formed the majority called outdated and said Congress “may draft another formula based on current conditions.”

The commission’s 402-page report found that states previously covered under the pre-clearance requirements passed new laws and voting procedures — strict voter identification laws, closing polling places, cutting early voting and removing names from voter registration rolls — that are hurting minority voting rights.

And it found the Justice Department can still enforce the Voting Rights Act through Section 2, but that is an “inadequate, costly, and often slow method” that allows elections to take place under laws later found to be discriminatory. It also limits the DOJ’s ability to supervise elections.

“This report puts a federal imprimatur on what we have been saying: the right to vote is under attack, and that diminishes our democracy,” said Vanita Gupta, president of The Leadership Conference on Civil and Human Rights.

The Voting Rights Act was reauthorized in 2006 unanimously in the Senate and with an vast majority in the House, and signed into law by Republican President George W. Bush.

Vermont Democratic Sen. Patrick J. Leahy introduced the Senate version of the bill, which has 49 co-sponsors, with Alaska Sen. Lisa Murkowski as the only Republican. In the House, Wisconsin GOP Rep. Jim Sensenbrenner has been pressing for his version of the bill and has 88 co-sponsors, but only nine of them are Republicans.

Watch: Hoyer Targets Voting Rights, Campaign Finance as Top Changes for Next Congress