Republican-dominated legislatures in at least four states are planning to consider allowing employees to bring guns to work, turning two of the party's traditional constituencies against each other: gun-rights supporters and businesses.

The measures, backed by the National Rifle Association, would allow workers in Alabama, Tennessee, South Carolina and Pennsylvania to keep the weapons locked and hidden in their cars in employee parking areas. Seventeen states have approved similar measures since 2003, according to a tally by the Law Center to Prevent Gun Violence in San Francisco.

The laws extend gun rights onto property controlled by private employers, prompting opposition from companies such as FedEx and Volkswagen. The proposals are creating a dilemma for Republicans, said Robert Spitzer, chairman of the political science department at the State University of New York at Cortland.

"The gun rights movement is now colliding against traditional business interests," Spitzer said. "It's a direct clash between a values issue and an economic one and both of these competing forces are particularly strong within the Republican Party."

The conflict has torn allegiances even among legislators who consider themselves strong backers of the Constitution's Second Amendment right to bear arms, as happened this year in Tennessee when the NRA, the Fairfax, Va.-based pro-gun organization, helped defeat Republican House caucus leader Debra Maggart in a primary. Maggart, who says she is a gun-rights supporter, had opposed a workplace firearms law because of concerns that it violated business and property rights.

"I am the most pro-Second Amendment person you can meet," Maggart said in an interview. "I had a perfect voting record with the NRA."

The law's proponents say the measures are needed to protect employees during their commutes. They say that employers who ban guns on their property are preventing workers from possessing their weapons when they commute, leaving them vulnerable to attack.

"This provides safety and protection for workers who oftentimes travel 20 to 50 miles to their jobs," said Alabama state Sen. Roger Bedford, D, who has introduced a parking lot gun law in the state's Republican-controlled legislature.

Bedford said he introduced the measure at the request of constituents. He couldn't point to any incident in which a commuter would have benefited from having a gun in the car.

"The problem we have is that businesses are being allowed to erode and take away our Second Amendment right to bear arms," he said. "The guns would only be allowed for legally licensed people, and they'd have to be locked up and out of sight."

NRA spokesman Andrew Arulanandam didn't return four calls for comment about workplace gun laws.

Opponents say the laws threaten employers' ability to control workplace safety and violate their property rights in the name of gun rights.

Workplace homicides average about 500 a year in the U.S., according to studies by ASIS International Foundation, an Alexandria, Va.-based security professional association, and by the Justice Department. Shootings accounted for 80 percent of workplace homicides between 2005 and 2009, with most involving robberies and 21 percent stemming from employee disputes, according to the 2011 Justice report.

Guns-to-work legislation has failed in 12 states in the past two years, including Alabama, Tennessee, Pennsylvania and South Carolina, where lawmakers say they'll push the measures as legislatures convene next year.

Darrell Scott, a lobbyist with the South Carolina Chamber of Commerce in Columbia, said the bill is widely opposed by the businesses in his state because it limits their ability to control to set policy on their property.

In Tennessee, FedEx, Volkswagen and the Tennessee Chamber of Commerce & Industry worked to defeat or modify the workplace gun law, opposing the NRA and the Tennessee Firearms Association, a group that promotes the right to bear arms.

"We believe that a property owner's right to provide a safe work environment trumps an individual's right to possess a firearm on the owner's property," said Maury Donahue, a spokeswoman for Memphis, Tenn.-based FedEx, in an e-mail.

Reid Albert, in charge of security for Volkswagen's Chattanooga operations, told lawmakers the measure could endanger 3,300 workers who park in company lots. Dismissals and parking lot arguments might both become more dangerous if guns are allowed in cars at the workplace, he said.

"Gun violence in the workplace is a real and ever present threat," he said in testimony earlier this year. "A law which prevents an employer from addressing this situation hinders my ability to protect the lives of all employees at Volkswagen, Chattanooga."

Richard Archie, a member of the Tennessee Firearms Association, said he pushed for the law to protect his 34-year-old daughter, a schoolteacher who commutes through dangerous parts of Jackson, Tenn.

House Republican leaders killed the bill in a procedural move after the NRA didn't agree to an opt-out provision or liability protection for property owners, said Maggart, who was the only one of those leaders with a primary challenger.

The NRA ran an advertising campaign against her, calling her an enemy of the Constitution who had killed gun rights behind closed doors. Billboards and pamphlets linked her with Democratic President Obama and special interests: "Bless her heart," said one. "Debra Maggart has lost her way."

"I couldn't overcome it," she said.

With assistance from Justin Blum and William Selway in Washington.