In a decision that could potentially have a major impact on the presidential election, the U.S. Supreme Court on Tuesday left intact a ruling that restored early voting rights for all Ohioans during the weekend before the Nov. 6 election.

Ohio Republicans had aimed to cancel early voting that weekend for everyone except members of the military, an effort challenged by the Obama administration and the Democratic Party, who argued it violated the Constitution’s equal protection clause. A U.S. appeals court blocked the plan last week, saying it likely violated the constitutional rights of non-military voters.

"While there is a compelling reason to provide more opportunities for military voters to cast their ballots, there is no corresponding satisfactory reason to prevent non-military voters from casting their ballots as well,” wrote Circuit Judge Eric L. Clay. “The public interest ... favors permitting as many qualified voters to vote as possible.”

The decision is not clear-cut. While all voters must be allowed to participate in the early voting period if it is offered, the court’s ruling said the decision could be left up to individual Ohio counties.

Democrats and Republicans have been focused on Ohio’s early voting debate for months. The option for early voting is reportedly heavily used by blacks, women, the elderly and low-income individuals, according to the appeals court -- demographics that tend to vote for Democratic candidates. One trial judge estimated that about 100,000 Ohio residents will vote in the three days leading up to Election Day.

No Republican presidential candidate has ever won the White House without winning Ohio, a battleground state that controls 18 of the Electoral College votes needed to snag the presidency.

Republican presidential candidate Mitt Romney originally alleged that the challenge to the early voting restrictions was part of the Obama administration’s plan to actually -- paradoxically -- restrict military voting in Ohio

“If I’m entrusted to be the commander-in-chief, I’ll work to protect the voting rights of our military, not undermine them,” Romney said in August.