President Barack Obama's pick to head the Commerce Department criticized a federal labor board's lawsuit against the Boeing Co. on Tuesday over the aerospace giant's decision to locate a new plant in South Carolina.

The nominee, John Bryson, recently stepped down from Boeing's board.

Bryson's comments came at a Senate Commerce Committee hearing on his nomination to succeed Gary Locke, whom Obama has named to become U.S. ambassador to China.

At the session, Republicans raised questions about Bryson's views on the environment and criticized the Obama administration for what they said is over-regulation of businesses. They also reiterated their threat to block Senate approval of Bryson's nomination until Obama sends the panel trade pacts with South Korea, Panama and Colombia.

Republicans asked Bryson about the National Labor Relations Board's suit against Boeing, which accuses the aircraft builder of opening a plant in South Carolina in retaliation against union workers in Washington state who went on strike in 2008. Sen. Jim DeMint, R-S.C., said the NLRB action was "an unprecedented violation of a company's ability" to locate its facilities where it wants to.