PALM BEACH, Florida, Nov 14 (Reuters) - President-elect Donald Trump said on Thursday that North Dakota Governor Doug Burgum, a wealthy former software company executive, will be his pick for interior secretary.

"He's going to head the Department of Interior, and it's going to be fantastic," a tuxedo-wearing Trump said at a gala at his Mar-a-Lago Florida retreat, adding that he would make an official announcement on Friday.

Burgum, 68, has portrayed himself as a traditional, business-minded conservative. He ran against Trump for the Republican presidential nomination before quitting and becoming a loyal Trump supporter, appearing at fundraisers and advocating for Trump on television.

At the gala, which featured tech billionaire Elon Musk, actor Sylvester Stallone and members of his incoming administration, Trump praised his latest cabinet picks and made some of his longest remarks since his presidential election victory speech.

"Nobody knew we were going to win it the way we won it," Trump said.

He teased Musk about his ongoing post-election stay at Mar-a-Lago. Musk is involved in some of Trump's meetings at the oceanfront property.

"I can't get him out of here. He just loves this place. And I like having him here," said Trump.

At the end of the event, Musk mounted the stage.

"The public has given us a mandate that could not be more clear. The people have spoken, the people want change," he said.

Since his victory, Trump has chosen several loyalists with little experience for key cabinet positions, stunning some allies and making clear that he is serious about reshaping - and in some cases testing - America's institutions.

MORE OIL AND GAS PRODUCTION

The Interior Secretary will oversee policies guiding the use of 500 million acres (202.3 million hectares) of federal and tribal land, a fifth of the nation's surface area.

Biden made the agency central to his climate change agenda by boosting the permitting of offshore wind and solar energy projects and creating a program to lease lands for conservation in the same way they are for development.

Burgum is expected to be tasked with increasing oil, gas and mineral production on federal lands and waters.

That job would likely involve ratcheting up new leasing in the Gulf of Mexico and on federal lands in oil-producing states like Wyoming and New Mexico.

Biden had pledged to stop new federal leasing for oil extraction but was prevented by the courts from doing so. Interior leadership under Trump could scrap Biden's five-year offshore drilling plan, which had a historically low number of auctions scheduled, and step up acreage offered at Congressionally-mandated onshore sales.

Drilling activity on federal lands and waters accounts for about a quarter of U.S. oil production and 12% of gas production.

The number of drilling permits approved on federal lands fell 16% between fiscal 2020, the last year of Trump's first administration, and fiscal 2023, according to data from the U.S. Bureau of Land Management. Acreage in new onshore leases slid 95%.

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Reporting by Steve Holland, Alexandra Ulmer and Eric Beech; Editing by Edwina Gibbs and Christian Schmollinger