North Carolina’s governor signed sweeping voting reforms into law Monday, approving a package of changes that drew stinging criticism and a legal challenge from the NAACP and others.

The American Civil Liberties Union joined two other groups in announcing they were filing suit against key parts of the reform package, hours after Gov. Pat McCrory signaled in a statement he had signed it without a ceremony.

Republicans who backed the legislation said it was meant to prevent voter fraud, which they claim is both rampant and undetected in North Carolina. Independent voting rights groups joined Democrats and libertarians in suggesting the true goal was to suppress voter turnout, especially among blacks, the young, the elderly and the poor.

“It is a trampling on the blood, sweat and tears of the martyrs — black and white — who fought for voting rights in this country,” said the Rev. William Barber, president of the state chapter of the NAACP. “It puts McCrory on the wrong side of history.”

The U.S. Supreme Court voted 5-4 last month to effectively halt the enforcement provisions of the landmark Voting Rights Act, enacted to outlaw racial discrimination against voters. North Carolina was among the states, mostly in the South, that were subjected to special federal enforcement, with requirements to get approval in advance before they could make even minor changes to voting laws.

That high court ruling cleared the way for North Carolina’s new Republican leadership to enact voting law changes without prior federal approval.

Barber called the Republican-backed measure one of the worst attempts in the nation at voting reform and said the National Association for the Advancement of Colored People considered the package an all-out attack on existing laws long seen as a model of voter participation.

Starting next year, the package is expected to be phased in gradually.

The legislation signed by McCrory and approved last month by state lawmakers requires voters to present government-issued photo IDs at the polls and shortens early voting by a week, from 17 days to 10. It also ends same-day registration, requiring voters to register, update their address or make any other needed changes at least 25 days ahead of an election. A high school civics program that registers tens of thousands of students to vote each year in advance of their 18th birthdays has been eliminated.

A provision also would end straight-ticket voting, in place in the state since 1925.

Critics said disclosure requirements intended to make clear who is underwriting campaign ads also would be weakened, and note political parties would be enabled to take in unlimited corporate donations. The cap on individual campaign donations also would rise from $4,000 to $5,000.

McCrory, who announced the signing in a statement, appeared in a 95-second message on YouTube giving his reasons and focusing solely on the voter identification component. The first-term governor cited laws that require people to present photo IDs to board airplanes, cash a check or apply for government benefits. “Our right to vote deserves similar protection,” McCrory said in the video.

Democratic Attorney General Roy Cooper was among those who had urged a veto.

“This bill was much more than just voter ID,” Cooper said in a statement Monday. “There were dozens of reasons to veto this bad elections bill with its restrictions on voting, more corporate campaign money and reduced public disclosure being just a few.”