The Supreme Court on Tuesday denied Democrats' effort to restore a so-called "Golden Week" in Ohio when voters could register and cast early ballots at the same time, handing voting rights advocates a rare defeat in the run-up to the fall elections.
The court's order came without comment and without any known dissents, including from the four justices named to the court by Democratic presidents.
A federal judge ruled in May that the 2014 law eliminating the practice violated the Constitution and the Voting Rights Act, but a three-judge appellate panel overruled that decision last month.
The Supreme Court's action is temporary, affecting only the fall elections. It has now denied efforts to block court rulings from taking effect in three voting rights cases. In North Carolina and Michigan, however, appeals courts had struck down state voting restrictions as discriminatory against minority voters.
All three cases represent challenges by Democrats or civil rights groups against laws passed by Republican-majority state legislatures, purportedly to crack down on voter fraud. Opponents of the laws say their true intent is to reduce minority turnout and help Republicans at the polls.
So far this year, courts have struck down such laws in North Carolina, Texas, Michigan and North Dakota, as well as a federal agency's decision that limited voting in Kansas and threatened Georgia and Alabama. Courts have ruled both for and against a Wisconsin law.
The Ohio restrictions and a photo ID requirement in Virginia have won court approval, though the Virginia case is being appealed.
"This much is perfectly clear: Ohio is a place where it is easy to vote and hard to cheat," said Ohio Secretary of State Jon Husted. "In fact, with voting now slated to begin in less than a month for the November election, Ohio is one of the easiest states in the nation in which to register and cast your ballot."
But David Pepper, chairman of the Ohio Democratic Party, said the high court's ruling would affect tens of thousands of potential voters "with no justification."