Civil rights groups are warning that as many as 10 million Hispanics may be deterred from casting ballots because of changes to voting laws.

In a report to be released Monday, the civil rights group Advancement Project cites the potential impact of newly restrictive photo identification laws, proof-of-citizenship requirements and late efforts in a few states to remove noncitizens from the voter rolls.

“It has the impact of scaring people and reminding them of [immigration] raids and other kinds of law enforcement that have been targeted toward these communities,” said Penda D. Hair, a co-director of the Advancement Project, part of a coalition of liberal groups that oppose the new voting laws.

Proponents of the efforts to tighten voting laws, including several secretaries of state, say they want to root out voter fraud and are not targeting particular demographic groups.

“The fact is our office only compared our voter rolls against DMV records where individuals showed proof of non-citizenship,” Rich Coolidge, spokesman for the Colorado secretary of state’s office, said in an e-mail. “To insinuate anything else is absolutely false and reckless. Unfortunately, some partisan groups attempt to leverage this effort for their own political gain.”

In-person voting fraud is rare, studies have shown, but there have been recent cases of absentee ballot fraud, and small numbers of noncitizens are registered to vote. In Colorado, the secretary of state’s office estimated last year that as many as 11,000 noncitizens were registered to vote. But after checking a federal immigration database, the state announced this month that 141 noncitizens were registered and as few as 35 had cast ballots.

Several of the states with more restrictive laws and procedures, such as Colorado, have large Hispanic populations. As the deadline to register voters approaches in many states, the Advancement Project’s report warns that the new rules are working against efforts to register Hispanics, the nation’s fastest-growing demographic.

Both President Obama and Republican nominee Mitt Romney are working hard to appeal to Hispanics, who could be key to winning important swing states if they turn out to vote in large numbers.

Advocacy groups have been trying for several years to increase the number of Latinos who vote. In 2010, 6.3 million Latinos who were eligible to vote reported that they were unregistered and 10.8 million said they did not vote, according to census figures cited by the report.

“At the end of the day, voting should be free, fair and accessible, and these barriers are standing in the way of an increasing demographic in this country,” said Judith A. Browne-Dianis, a co-director of the Advancement Project.

A dozen state legislatures passed rules last year requiring voters to present state-issued photo IDs, according to the National Conference of State Legislatures, although in four states the laws were vetoed by Democratic governors.

Pennsylvania’s governor signed a voter ID bill in March that is still being litigated, with opponents presenting studies showing that blacks, Hispanics and others in urban areas are less likely to have the required ID.

In addition, 16 states — including Colorado, Florida and New Mexico — have attempted to “purge” noncitizens from registration lists. The Advancement Project cited examples of purges incorrectly flagging the names of naturalized citizens, putting them at risk for having their voter registration invalidated.

Florida halted an effort to remove noncitizens from lists when it became known that the database used by the state to check citizenship was out of date.

Denver resident Veronica Figoli, who immigrated from Venezuela in 1999, was among the legally registered voters in Colorado whose name was flagged for removal from voter rolls. The letter that she received said it was “extremely important” that she affirm her citizenship or withdraw from the voter rolls, which she said made her feel like a “second-class citizen.”

“To get this letter was kind of insulting,” said Figoli, who became a citizen in 2011 after what she said was a costly and stressful process. “There are so many steps and it is so confusing, and it’s expensive. And you are dealing with government and that makes you uncomfortable.” When she got the letter, she said, “I questioned myself.”

Figoli returned the required paperwork but said that others might be more fearful.

“I have a friend who said, ‘I wouldn’t do anything. . . . What if they revoke my citizenship?’ ” Figoli said. “The fear is there.”

Melinda Aguirre, who was born in Denver, also received a letter in English and Spanish questioning her citizenship. “I don’t even speak Spanish,” she said. “It’s just a bunch of [bull] what they are doing with certain people. My mom didn’t get this letter. My brother didn’t get this letter. Their last name is Roybal. But the Aguirres did.”

John Fund, a conservative columnist and author of “Stealing Elections: How Voter Fraud Threatens Our Democracy,” said recent polls show that advocates of cleaning up the voter rolls have public opinion on their side and that they are being unfairly accused of racism. “It is very unfortunate that this issue has been used by groups who want to yell racism in a crowded political theater,” Fund said. “This is not the way to debate these issues.”

Still, the National Council of La Raza, which has been working with a network of groups to register Hispanic voters, was one of a dozen civil rights groups that said last week that voting rights are in a “state of emergency.”

“Part of our frustration is that the debate over the voter integrity process has become a polarized thing,” said Clarissa Martinez De Castro, the group’s director of immigration and national campaigns. “It’s almost like voters have become guilty until proven innocent.”

Ana Navarro, a Republican campaign consultant in Florida, said she doesn’t expect Hispanics there to be dissuaded from registering or voting.

“I don’t get the sense that the average voter is out there ready to set their hair on fire over the voting law changes,” she said in an e-mail. “Political campaigns are in full swing in Florida and there’s just too many substantive issues like the economy, high unemployment, Medicare, and housing, that Floridians are worried about. . . . Ready or not, whether you like or dislike the changes to the process, voting is upon us.”

Floridians start getting absentee ballots in a couple of weeks, and in most states, voter registration closes 30 days before the election.