WASHINGTON — The Justice Department on Monday sued North Carolina for alleged racial discrimination over a tough new voting law that shortens early voting and imposes other restrictions that heavily affect minority voters.

“By restricting access and ease of voter participation, this new law would shrink, rather than expand, access” to voting, Attorney General Eric Holder told a news conference. “Allowing limits on voting rights that disproportionately exclude minority voters would be inconsistent with our ideals as a nation.”

The lawsuit is the latest effort by the Obama administration to counter a Supreme Court decision that struck down the most powerful part of the landmark Voting Rights Act and freed states, many of them in the South, from strict federal oversight of their elections.

Within days of the Supreme Court ruling, North Carolina’s legislature “took aggressive steps to curtail the voting rights of African Americans,” Holder told reporters, calling it “an intentional attempt to break a system that was working.”

He said that in the 2008 and 2012 general elections, African-American voters dramatically increased their participation rates across North Carolina, and more than 70 percent of African Americans who voted in those elections cast ballots during the early voting period before Election Day.

North Carolina’s new law scales back the period for early voting by seven days and includes a stringent photo ID requirement for voters.

State Senate President Pro Tempore Phil Berger and House Speaker Thom Tillis issued a statement that rejected Holder’s argument. “The Obama Justice Department’s baseless claims about North Carolina’s election reform law are nothing more than an obvious attempt to quash the will of the voters and hinder a hugely popular voter ID requirement,” they said.

“The law was designed to improve consistency, clarity and uniformity at the polls and it brings North Carolina’s election system in line with a majority of other states,” the two lawmakers said. “We are confident it protects the rights of all voters, as required by the U.S. and North Carolina Constitutions.”

Republican lawmakers in southern states insist the new measures like the one in North Carolina are needed to prevent voter fraud.

“The proof of that is simply not there,” said Holder. Studies show that “this concern about vote fraud is something that is made up in order to justify these restrictive — and I think at a minimum — partisan actions,” he said.

The North Carolina law outlines a gradual implementation timeline, beginning with the 2014 elections, for informing voters and enacting the photo ID requirement, until the law is fully enforced in 2016.

Democrats and civil rights groups argue that the tough new laws are intended to make voting more difficult for minorities and students, voting groups that lean toward Democrats, in states with legacies of poll taxes and literacy tests.

North Carolina is among at least five Southern states adopting stricter voter ID and other election laws. On Aug. 22, the Justice Department sued Texas over the state’s voter ID law.

The North Carolina lawsuit challenges the state law’s elimination of the first seven days of early voting opportunities and its elimination of same-day voter registration during the early voting period. Same-day registration allows voters to cast a ballot immediately after showing election officials proof of their name and home address.

The Justice Department challenge also is aimed at a provision eliminating the counting of certain types of provisional ballots by voters who cast ballots in their home counties but do not vote in the correct precincts.

Finally, the federal government is challenging a provision in the new law that requires voters to present government-issued identification at the polls in order to cast ballots. In North Carolina, a recent state board of elections survey found that hundreds of thousands of registered voters did not have a state-issued ID. Many of those voters are young, black, poor or elderly.