President Obama on Friday said that Republicans were behind the biggest threat to voting rights in decades.

“The principle of one person, one vote is the single greatest tool we have to redress an unjust status quo. You would think there would not be an argument about this anymore,” said Obama in an address to Rev. Al Sharpton's National Action Network conference in New York City.

“The right to vote is threatened today in a way that it has not been since the Voting Rights Act became law nearly five decades ago,” he added.

The president directly blamed Republicans, saying new voting laws in states across the country would make it harder for Americans to get access to the ballot box.

“It's a fact. This recent effort to restrict the vote has not been led by both parties. It's been led by the Republican Party,” said Obama.

Republican lawmakers in states are pushing more stringent laws requiring identification or verification before voting, saying it is necessary to combat fraud at the polls. But Democrats say those measures disenfranchise poor and minority voters and are intended to give the GOP a partisan boost.

Obama charged that supporters of voter ID laws had used “bogus” claims of fraud to build support and urged those at the conference to fight back.

“There's a reason why those who argue that harsh restrictions on voting are somehow necessary to fight voter fraud are having such a hard time proving any real widespread voter fraud,” said Obama.

He said that a recent study found only 10 cases of people impersonating voters to illegally vote over 12 years.

“For those of you who were math majors, that's a percentage that is 0.00002 percent,” said Obama.

“That's not a lot,” he added. “So let's be clear, the real voter fraud is people who try to deny our rights by making bogus arguments about voter fraud.”

The Obama administration has vowed to contest voter identification laws across the country, with Attorney General Eric Holder bringing suit against the state of Texas to prevent its law from taking effect.

Democrats have also made an effort to push back against new voter measures ahead of November's midterm elections.

In a video for the Democratic National Committee earlier this week, Vice President Joe Biden slammed those new laws as well as the Supreme Court decision striking down a key part of the Voting Rights Act.

“I thought at that time the only debate we would be having at that time would be how to expand the voting franchise, but last year when the Supreme Court cut the heart out of the Voting Rights Act, it opened up the floodgates to voter suppression,” Biden said, urging Democratic activists to volunteer to help voters.