COLUMBIA - A Republican-backed bill requiring registration by party to vote in party primaries suffered a setback Wednesday when a House subcommittee delayed action on it until a study of costs is complete.

South Carolina's existing system allows registered voters to pick their party ballot on primary day. They can be Democrats one year and Republicans the next.

The proposed system would admit only those registered in a party to that party's primary, but voters would be allowed to switch up to 30 days before an election.

Greg Shorey, a former state GOP chairman, said the existing system invites "intrusion" by people who try to influence another party's nominees.

A majority of Republicans support the change in a resolution passed in last year's state and county conventions, Shorey said.

Primaries are not elections and should not be open to everyone, he said. They are party functions and if open primaries continue, "it will destroy our party system," he said.

"It is clear to me that we have had raiding in certain primaries," said Rep. John Graham Altman, R-Charleston.

Democrats generally oppose the change. Rep. Walt McLeod, D-Little Mountain, told the subcommittee he hears that people are weary of partisanship and most consider themselves independent.

"Vote for what's in the best interests of the citizens of this state and don't have party registration," McLeod said.

Marilyn Bowers, director of elections and voter registration in Pickens County, said the S.C. Association of Registration and Election officials passed a resolution last week opposing the change mostly because of the costs.

State Election Commission Director Marci Andino said her agency is not taking a position, but that the required mailings to inform voters of the change would cost $2.2 million, more than the commission's annual budget.

Rep. Thad Viers, R-Myrtle Beach, a member of the subcommittee, said he is concerned about giving power to party officials to determine who can vote in primaries.

"Certain elements in our party are trying to control everything, including legislators," Viers said.

The panel will not meet again until the economic study is complete, and members had no estimate of when that would be. A similar bill awaits action in the Senate.