Updated

Republican presidential candidate Mitt Romney, fresh from picking up former rival Tim Pawlenty's endorsement, criticized the Obama administration's links to organized labor, arguing that a National Labor Relations Board's complaint against Boeing is White House payback to unions.

Touring the aeronautics giant's new $750 million plant in South Carolina, Romney drew loud applause from about 60 people in the North Charleston City Council Chambers when he suggested that any stimulus package to boost the economy should include legislation telling the NLRB to drop its Boeing complaint. The package also should block the agency from pursing similar action elsewhere in the country.

The agency has filed a complaint against Boeing alleging that the plant, which opened earlier this summer in North Charleston, was built in violation of labor laws to avoid unionized labor in Washington state. The NLRB claims Boeing opened the new plant to punish Washington state workers for past strikes and wants the company to return the work to Washington.

"It's an egregious example of political payback where the president is able to pay back the unions for the hundreds of millions of dollars they have put into his campaigns at the expense of American workers," Romney said.

South Carolina AFL-CIO President Donna Dewitt said that Romney seems more interested in making political points and supporting Boeing, he company he has reported having investments in.

She said that the NLRB is a neutral, independent agency and is being attacked by Republican politicians simply for asking that Boeing obey federal law.

Romney appeared with former Minnesota Gov. Pawlenty, who endorsed his candidacy earlier Monday. Pawlenty, who quit the GOP race last month after a poor showing in the Iowa straw poll, said the former Massachusetts governor is the candidate who "possesses the unique qualifications to confront our severe economic predicament."

Romney said Pawlenty would be a good addition to any national ticket but Pawlenty said he was not interested.

The Boeing plant is the single largest industrial investment in South Carolina history and the complaint has drawn widespread criticism from elected officials, both Republican and Democrat. Gov. Nikki Haley, a Republican whose campaign for governor got an early endorsement last year from Romney, has promised Boeing would have complete support from South Carolina.

But Romney said that uncertainty about the NLRB complaint has prompted Boeing suppliers to hold off locating in the state.

During his appearance, Romney criticized several administration labor policies and said automatic union dues should not be used by unions to pay for politics.

"I'm very concerned our president has pursued labor policies that are destructive to industry, to hiring and to job growth," Romney told the audience. "Those policies are one reason America is having a very difficult time coming out of this economic slowdown."

If elected, he said, he would encourage states to pass right to work laws like South Carolina has done.