TALLAHASSEE (AP) – Critics say a new Florida election law that went into effect Thursday with Republican Gov. Rick Scott’s signature will discourage some likely Democratic voters, including minorities and young people, from registering or casting ballots.

The law reduces early voting hours. It also requires voters who make address changes at the polls to cast provisional ballots that may not be counted.

Sponsors in the GOP-controlled Legislature argued the law, similar to proposals that have been introduced by Republicans in about 25 other states, is needed to prevent election fraud.

“It is paramount to our democracy that we protect the credibility of Florida elections,” House State Affairs Committee Chairman Seth McKeel, R-Lakeland, said in a statement. “Each unlawful ballot takes away the vote of a Florida citizen casting a legal ballot.”

Florida Democratic Party Chairman Rod Smith called it a “voter suppression” law and “nothing more than a power-grab by Republicans.”

Scott signed the bill (HB 1355) without ceremony or comment, but it drew a firestorm of reaction from Democrats and other opponents, including some nonpartisan groups, saying it’s an assault on voters.

“If it weren’t so grotesquely un-American, you’d almost want to congratulate them for the audacity and efficiency of the attack,” said Howard Simon, executive director of the American Civil Liberties Union of Florida.

“With just one bill, they made it harder to register to vote, harder to cast your vote and harder to have your vote counted,” Simon said in a statement.

Secretary of State Kurt Browning said the law will be submitted to the U.S. Department of Justice for preclearance under the federal Voting Rights Act to determine if it discriminates against minority voters. If U.S. Attorney General Eric Holder determines that it does, the law cannot be enforced.

Until the Justice Department makes a decision the law will be in effect everywhere except five counties for which preclearance is required, Browning said. That includes a special election Tuesday in Miami-Dade County for several offices including county mayor and state representative. A lawsuit has been filed in Miami-Dade challenging the county’s decision to cancel early voting Sunday to comply with the anticipated new statute before Scott signed it.

Browning, a Scott appointee who also held the post under former Gov. Charlie Crist, acknowledged there’s been little election fraud in Florida but said the law is intended to keep it that way.

“Florida wants to be more proactive than reactive,” Browning said.

The ACLU, League of Women Voters and possibly others are considering court challenges to the law itself if it receives Holder’s approval.

The law reduces early voting from two weeks to one, but Browning said the total number of hours won’t necessarily change. That’s because early voting polling places can be open for 12 hours instead of only eight hours each day at the discretion of local election officials. The law, though, will let smaller counties, where there is less demand for early voting, reduce hours to save money, Browning said.

Another provision requires voters to cast provisional ballots if they make address changes from one county to another at the polls on Election Day. Canvassing boards can reject a provisional ballot if it lacks evidence showing the person casting it was entitled to vote. Voters have two days after Election Day to offer such evidence.

Browning, who is given more authority by the new law, said he will issue an order to local election officials that they must count provisional ballots unless there’s some evidence of fraud. That’s even if voters do not provide any more information than the address change they made on Election Day.

Critics say the provisional ballot requirement will disproportionately affect minorities and college students because they tend to move frequently.

The League of Women Voters has decided to halt voter registration drives in Florida due to new requirements the law puts on such activities. Those registering voters would have to register themselves with the state, file regular reports and turn in completed voter registration forms within 48 hours of being signed or else face a $50 fine for every late form.

“Gov. Scott takes Florida back in time today with his approval of cumbersome regulations that will make it harder for eligible Floridians to be engaged and active in their government,” said Deirdre Macnab, the league’s state president.

Macnab said the league believes the bill contains provisions that violate federal law because they have a disproportionate effect on black and Hispanic voters. She said studies show those minorities are twice as likely to register via third party groups such as the league and Boy Scouts.

“I do not see the 48 hours as being onerous,” Browning said. He noted the groups have submitted forms within that time frame in the past although the old law allowed up to 10 days.

The legislation passed largely along party lines in the House and Senate.