US President Joe Biden's pick for transportation secretary, Pete Buttgieg, has expressed his support for the Jones Act.

Responding to a question from Senator Maria Cantwell, a Democrat from Washington state, the former small city mayor told the Senate Commerce, Science and Transportation Committee on Thursday that the cabotage law was critical for domestic shipping.

"I share your support for the Jones Act," Buttgieg said.

"It's so important to a maritime industry that creates hundreds of thousands of jobs as well as the shipbuilding industry here in the US."

It was the only mention of the Jones Act or shipping in the two-hour, 20-minute hearing and Buttgieg gave no further details on what a department under his control would do for the industry.

Should Buttgieg be confirmed by the full Senate and take over as head of the Department of Transportation, he would lead the US agency including the Maritime Administration and the Federal Maritime Commission.

The two boards respectively promote and regulate the shipping industry domestically.

He would also be tasked with replacing former Maritime Administrator Mark Buzby, who resigned his position shortly after the riots on Capitol Hill earlier this month.

On Thursday, a deputy administrator, Lucinda Lessley, was appointed by Biden along with a slew of other posts in the Department of Transportation. She will serve as the acting administrator, the Department of Transportation told TradeWinds.

Neither Biden nor Trump had much to say on the Jones Act during the campaign. Biden describing himself as a "strong advocate" for the law, while Trump spent his tenure in the White House mostly resisting calls for waivers.

If confirmed, Buttgieg would replace Elaine Chao, the first member of former president Donald Trump's cabinet to resign after the riot.

Chao's father founded New York-based bulker owner Foremost Group and her sister, Angela Chao, currently serves as chief executive.

Buttgieg served as an intelligence officer in the US Navy before being elected mayor of South Bend, Indiana, a city of roughly 100,000 people.

He had launched a campaign for president ahead of the 2020 election, before dropping out to throw his support behind Biden.

Buttgieg's confirmation would be the first for an openly gay American.

Trump had previously appointed another openly gay man, Richard Grenell, to the post of acting director of national intelligence.