For two men who both claimed Monday to have the interests of American workers at heart, former Massachusetts Gov. Mitt Romney and AFL-CIO president Richard Trumka could not have offered more different appraisals of the National Labor Relations Board.

Romney kicked off the workweek by becoming the latest Republican presidential candidate to tour Boeing's North Charleston plant and then rip the NLRB for initiating a complaint against the aviation giant.

He said President Barack Obama had put "labor stooges on the NLRB to pursue a political payback strategy, and the most serious consequence of that strategy is what's happened here in South Carolina."

"There is, without a question, an egregious example of political payback where the president is able to pay back unions for the hundreds of millions of dollars they put in his campaign at the expense of American workers, American jobs," Romney said to applause from supporters at North Charleston City Hall.

Romney proposed that the U.S. House of Representatives insert language into Obama's jobs bill that would foreclose the NLRB's case against Boeing, which is accused of building the South Carolina plant as a way to punish union workers for past strikes. The company has denied that.

In a teleconference the AFL-CIO set up to denounce an anti-NLRB bill introduced by U.S. Rep Tim Scott, Trumka said Romney was interested in "scoring cheap political shots and points."

"We would expect it from him," he said. "He is an investor in Boeing."

Trumka called Scott's bill "The Outsourcer's Bill of Rights" and said it would leave the NLRB powerless to protect workers.

At least the third presidential candidate to tour the 787 Dreamliner factory, Romney made the rounds with former Minnesota Gov. Tim Pawlenty. Boeing officials have forecast 5,000 to 7,000 jobs at the plane-making plant, but despite that healthy projection, suppliers are hesitant to follow, Romney said.

"They spoke about the fact that by virtue of the NLRB's decision to try and fight this plant, that suppliers are holding off, that their decisions to come to South Carolina will be based, in part, on whether or not there's going to be a Boeing facility working there long-term," Romney said. He said the case has had a "chilling effect."

"And people have to wonder, 'Has America gone nuts?'" Romney said.

Later, on the AFL-CIO teleconference, University of Texas law professor Julius Getman seemed to wonder the same thing, puzzling over the Republican outrage at the NLRB's investigation of Boeing's decision to expand Dreamliner production outside of Everett, Wash. He said the NLRB has been taking this sort of action for over 70 years.

"Suddenly that becomes radical," he said. "Amazing."

Trumka insisted the NLRB case "has nothing to do with South Carolina," as Boeing could bring jobs back from Asia to satisfy the NLRB. He warned South Carolina workers that a day might come when they want to strike for better working conditions or wages.

"Boeing can say to them, 'Too bad South Carolina,' " and move to Mexico, Trumka said. "They wouldn't like that. I wouldn't like that."

Reach Brendan Kearney at 937-5906 and follow him at twitter.com/kearney_brendan.