COLUMBIA, S.C. (AP) -- Anyone registering to vote in South Carolina would have to show a passport, birth certificate or naturalization documents under a bill being pushed by Republican lawmakers.

Supporters of the bill say it will protect elections by ensuring illegal immigrants or other noncitizens can't cast a ballot. Critics say it's just a GOP move to hassle people who might vote for Democrats.

The measure would apply only to people registering after it becomes law, not voters already on the rolls.

"The only people stifled from voting are those who can't legally vote," said Rep. Alan Clemmons, who leads a subcommittee that approved the measure earlier this year.

By law, only citizens can vote. Clemmons said requiring residents to verify what they put on their voter application form is not a burden.

"It's a simple matter to produce a birth certificate," the Myrtle Beach Republican said, adding he'll volunteer to help secure one for any South Carolinian without it.

But Democrats contend poor and rural residents are less likely to have a birth certificate, much less a passport, and that getting one takes time and money. Some older residents weren't even born in a hospital, said Brett Bursey, executive director of the state Progressive Network.

The measure is "aimed squarely at suppressing the Democratic vote," said the liberal activist.

In January, the Democratic presidential primary drew nearly 87,000 additional South Carolina voters than the Republican contest, a stunning figure in a state where the GOP controls both chambers of the Legislature, all but one statewide office and six of eight seats in the U.S. House and Senate.

At a House Judiciary Committee meeting last week, Rep. Todd Rutherford, D-Columbia, said the bill harkens back to the Jim Crow era of poll taxes and reading requirements meant to keep blacks from voting.

"We're imposing a chilling effect on people who want to register to vote, and I have real problems with that," said Rep. David Weeks, D-Sumter.

As debate dragged on, House members postponed a vote on the bill until the next committee meeting later this month.

If approved, the legislation could make South Carolina only the second state nationwide to require proof of citizenship to register to vote. Arizona passed a similar law in 2004 that has been upheld in federal court, though the challenge continues, said Tim Storey, an elections expert with the National Conference of State Legislatures.

Legislators in at least 15 states, including South Carolina, are considering such bills, he said.

There is no evidence of a noncitizen ever trying to vote in a South Carolina election, said state Election Commission spokesman Chris Whitmire.

Clemmons and other proponents contend the state needs to safeguard elections before the escalating immigrant population leads to an illegal voting problem.

The latest Census estimate puts South Carolina's Hispanic and Latino population at roughly 130,000. But advocates say it's probably more than three times that number, and climbing.

Bursey accused Republicans of using the fear surrounding illegal immigration to suppress Democratic votes. "Today's boogeyman is immigrants," he said.

The bill's sponsor, Rep. Gloria Haskins, said her intent was not to make everyone submit proof of citizenship when registering, but only people born in another country, as she was. Haskins, who emigrated from Colombia with her family at 12 years old, said she's more concerned with immigrants who are here legally but are not citizens trying to vote, and she will try to amend the bill.

The Greenville Republican, who introduced the measure in January 2007, said voting is among the greatest right Americans have, but those born here often take it for granted. She said becoming a citizen at 24 years old was one of the proudest moments of her life, and agrees making every would-be voter prove their citizenship is too restrictive.

"I don't want to stifle the process at all," Haskins said. "My intention is to maintain the integrity of the process. If you're born here, you don't need to prove you can vote."

But Clemmons said trying to limit the bill to those born elsewhere isn't feasible and could cause profiling problems. An elections official can't tell by looking at people or their applications whether they're born in America, he said.