WASHINGTON — Boeing found itself in a growing political storm Monday as GOP presidential candidate Mitt Romney visited the company's new $750 million plant in South Carolina and House Republicans prepared to pass a bill aimed at stopping the federal government from interfering in where companies can locate their facilities.

The maneuvers are part of an effort to use the Chicago-based company to prove that the Obama administration has gone overboard in protecting the interests of U.S. labor unions.

Visiting the plant before participating in a Republican presidential debate in Florida on Monday night, Romney said a complaint filed by the National Labor Relations Board (NLRB) to shutter the South Carolina plant is the White House's payback to labor unions.

In its complaint, the NLRB alleged that Boeing built its South Carolina plant in violation of labor laws to avoid using more unionized labor in Washington state.

Labor unions fought back by accusing Romney of trying to advance his personal interests, noting that he has financial holdings in Boeing.

In a conference call with reporters, AFL-CIO President Richard Trumka said Republicans are trying "to protect a company charged with breaking the law."

To help make its case, the AFL-CIO included a Boeing worker from Washington in its conference call.

Patrick Bertucci, a third-generation Boeing employee from University Place, Pierce County, who has worked for the company for nearly 15 years, said he welcomed the NLRB's involvement: "I was proud to see someone standing up to defend our rights, even against a big company like Boeing."

Romney criticized the NLRB's decision to sue Boeing over its opening of the 787 Dreamliner plant in right-to-work South Carolina, saying the board's action had a "chilling effect on additional growth here in South Carolina."

South Carolina AFL-CIO President Donna Dewitt accused Romney of trying to score "cheap political points" for his election bid by supporting Boeing.

On Capitol Hill, House Republicans said their Boeing legislation would be one of the first post-recess bills aimed at getting rid of regulations that inhibit job growth.

The bill is sponsored by Republican Rep. Tim Scott of South Carolina and is scheduled for a vote Thursday, his office said.

In a briefing with reporters, House Majority Leader Eric Cantor of Virginia referred to the NLRB complaint as an "overbearing action" and said he was concerned that the board was setting a precedent.