WASHINGTON (AP) — The House is poised to pass a measure that would undermine the government's high-profile labor case against Boeing Co. by curtailing the National Labor Relations Board's enforcement power.

The bill would prohibit the federal agency from ordering any employer to shut down plants or relocate work, even if a company illegally retaliates against unionized employees.

House Republicans say the board should not have the power to dictate where a private business can locate. GOP lawmakers have vilified the NLRB for filing a complaint in April that alleges Boeing punished union workers in Washington state when it opened a new production line for its 787 airplane in South Carolina, a right-to-work state.

"This action is having a chilling effect on businesses all across the country," said Rep. John Kline, R-Minn., chairman of the House Education and the Workforce Committee.

The bill is likely to pass the GOP-controlled House easily on Thursday, but it isn't expected to get far in the Senate, where Democratic leaders have no plans to let it come to a vote.

Republicans and their allies in the business community have gone after the NLRB for more than a year, as the agency has issued a spate of union-friendly decisions and rules. But the Boeing case has become a major political issue and a rallying cry for GOP presidential candidates courting voters in South Carolina's early primary stakes.

Union leaders say the bill would eviscerate the board's ability to enforce labor laws when companies simply eliminate work to get rid of employees who are pro-union.

The legislation "would undermine the basic rights of workers to organize and bargain collectively by permanently eliminating the NLRB's only effective remedy against a wide range of illegal conduct," Bill Samuel, government affairs director at the AFL-CIO, said in a letter to lawmakers.

Boeing has denied the allegations, saying it opened the Charleston, S.C., plant for valid economic reasons. The case is pending before an administrative law judge in Seattle and could last years.

The complaint by the board's acting general counsel, Lafe Solomon, does not seek to shut down the Boeing plant. The company would be required to move the new 787 production lines back to Washington state. But Boeing officials say the South Carolina facility was built specifically for construction of the 787. The company claims a ruling for the government would effectively require the company to close the $750 million plant and lay off more than a thousand new workers there.

Solomon said the decision to file a complaint was not politically motivated, but based strictly on evidence that Boeing violated the law. He said Boeing executives made a number of public statements indicating the new plant was built in South Carolina out of frustration over costly strikes by the Machinists union in Washington state, including a 58-day work stoppage in 2008.

"The decision had absolutely nothing to do with political considerations, and there were no consultations with the White House," Solomon said in a statement this week. "Regrettably, some have chosen to insert politics into what should be a straightforward legal procedure."

Boeing officials claim the board took the statements out of context and say they can point to a number of legitimate reasons for locating the new production line in Charleston.

President Barack Obama has not taken a formal position on the case, saying he is reluctant to interfere with an independent government agency. Obama has said companies need to have the freedom to relocate but must follow the law when doing so.