Stricter ID laws and other controversial voting restrictions, passed this year by several Republican-controlled legislatures, are hitting legal roadblocks that could keep many of the measures from taking effect before the November elections.

Curbs on early voting, new ID requirements and last-minute efforts to rid voter lists of noncitizens have been met with vigorous opposition from the Justice Department and civil rights groups, and in some cases, the provisions have been blocked by federal or state judges.

“There has been a real push-back by the courts to these widespread efforts to restrict the vote,” said Wendy Weiser, director of the Democracy Program at the Brennan Center for Justice at NYU School of Law, which opposes the new laws. “If those seeking to suppress the vote won round one, round two seems to be going to the voters.”

Supporters of the laws argue that they will ensure that elections are fair and will cut down on the potential for voter fraud. Democrats contend that the laws disproportionately affect people who tend to vote for their candidates.

Florida, viewed by both President Obama and Republican rival Mitt Romney as key to the election, passed several voting laws that have been challenged. Last week, a federal judge in Florida threw out a new state law that groups registering voters submit the registration cards within 48 hours or face steep fines, calling the mandate onerous. Justice Department officials have also challenged an effort by Florida’s Republican secretary of state to remove noncitizens from voter registration lists, saying it is illegal to conduct such a purge this close to an election.

Florida Gov. Rick Scott (R) defended the review of the lists.

“We need to be reviewing our voter rolls and making sure only those individuals who have the right to vote . . . are voting,” Scott told WNDB radio in Daytona Beach.

In a letter to the Department of Justice, Florida Secretary of State Ken Detzner argued that the state has violated no federal voting laws and gave no indication that Florida will stop its effort to clean up voter registration lists -- setting up a showdown with federal authorities.

Last year, new ID measures were introduced in 34 states and passed in Kansas, Mississippi, Rhode Island and Wisconsin. Alabama, South Carolina, Tennessee and Texas tightened existing voter ID laws to require a photo ID. Legislation in five other states was vetoed by their governors, according to the National Council of State Legislatures.

Since then, two state judges in Wisconsin have ruled its voter ID law unconstitutional. A Missouri court threw out a ballot initiative that would have allowed voters to decide whether photo IDs should be required, calling the language “misleading.”

The Justice Department has challenged ID laws in South Carolina and Texas under Section 5 of the Voting Rights Act, which could keep those laws from taking effect before November. Speaking to a group of black politicians and church leaders last week, Attorney General Eric H. Holder Jr. said that his department is committed to “aggressively enforcing the Voting Rights Act” and that it opposed the ID laws in the two states because of their impact on minority voters. The Voting Rights Act requires some states or counties with a history of discrimination to receive federal approval before changing their voting laws.

Texas Attorney General Greg Abbott called Justice’s stance “quite stunning” and “obviously political.”

“In Texas we have been involved in cases where votes have been cast for dead people, alive people have voted twice and foreign nationals have been allowed to vote illegally,” said Abbott, whose office has won convictions in 50 cases of voter fraud in the past eight years. “It is the state’s right to protect the integrity of the ballot box.”

The law being contested in Texas is often cited as unfair because it allows gun permits as identification but not student IDs, with opponents arguing that gun owners are more likely to support Republicans while students may lean toward Democrats.

Penda Hair, co-director of the Advancement Project, which has filed lawsuits against the more-restrictive voting laws in several states, said she views the Texas law and others as a result of “politicians trying to pick the voters that will vote for them. . . . There is a coordinated, systematic assault on the voting rights of the most vulnerable voters, voters of color, young people and seniors.”Opponents say there have been few cases of voter fraud, given the millions of ballots cast and compared with the high number of poor and minority voters who would be affected.

Twenty-five percent of African American voters do not have a valid government-issued photo ID, compared with 8 percent of whites, according to a study by the Brennan Center. The report also found that 15 percent of voters earning less than $35,000 per year do not have such an ID.

But Abbott said the Supreme Court is on his side. Before the 2008 election, the high court upheld a voter ID law in Indiana. The Justice Department has said that the law in Texas, which must seek preclearance for its laws under the Voting Rights Act, would have a discriminatory impact on the state’s Hispanic population.

A trial to determine whether the Texas law can take effect is scheduled to begin July 9.

The ACLU and several other civil rights groups have also filed suit to stop the voter ID law in Pennsylvania. That trial is set for late July.