Wilbur Ross (M) in the hearing [Photo by Chen Weihua/China Daily]

President-elect Donald Trump's pick for commerce secretary said Wednesday that he favors "sensible trade," is pro-union and believes his vast business dealings have given experience fighting other countries' unfair trade practices.

Billionaire investor Wilbur Ross cited his relationship with the United Steelworkers Union, which has endorsed him for the Cabinet post, as proof that he will work to protect American jobs.

"I'm pro-trade. But I'm pro-sensible trade, not trade that is detrimental to the American worker and to the domestic manufacturing base," Ross told the Senate Commerce, Science and Transportation Committee.

"I think I've probably had more direct experience than any prior cabinet nominee has had with unfair trade in the steel business, in the textile business, in the auto parts business and other sectors," Ross said.

Worth an estimated $2.9 billion, Ross has extensive business ties around the globe. Supporters say that makes him ideal to represent American business interests abroad.

"I believe his extensive management experience in the private sector, and his understanding of the challenges faced by workers and businesses alike, will equip him well for the job of leading the Department of Commerce," said Sen. John Thune, R-S.D., the committee chairman.

During Ross' hearing, Thune revealed that Ross had a household employee from 2009 to 2016 who could not provide documentation that he or she was in the U.S. legally.

Ross said the employee provided a driver's license and a Social Security number when hired. Ross said he rechecked the documentation for all of his household employees after he was nominated, and the employee could not provide it. Ross said the employee was fired.

"We did the best that we thought we could do in order to verify the legality of the employment and it turned out that was incorrect," Ross said. "But we did pay all the withholdings, so did that employee."Such transgressions have derailed cabinet nominees in the past. But Sen. Bill Nelson of Florida, the top Democrat on the committee, questioned Ross only briefly about it.