Democrats have sharply criticized the firing of general CQ Brown -- the previous chairman of the Joint Chiefs of Staff -- and other top officers, accusing Trump and Defense Secretary Pete Hegseth of seeking to ensure the military is led by people loyal to the president.

Retired lieutenant general Dan Caine sought to allay such concerns about his nomination, saying that if confirmed, "I'll continue the traditions and standards of my oath of office and my commission as a nonpartisan leader who will always strive to do the right thing."

Caine said that guarding against politicization of the military "starts with being a good example from the top and making sure that we are nonpartisan and apolitical and speaking the truth to power every day."

"The nation and the Constitution all require a nonpartisan military," he said.

Caine also addressed an account that he had put on a "Make America Great Again" hat while meeting with Trump in the past, suggesting the president may have been recalling actions by someone else.

"For 34 years, I've upheld my oath of office and my commitment to my commission, and I have never worn any political merchandise," said Caine, who was nominated by Trump to replace Brown in a highly unusual move earlier this year.

- 'Razin' Caine -

Nominees for chairman of the Joint Chiefs must have served as the head of a military branch, as a commander of a combatant command or as vice chairman -- none of which Caine has done -- but the president may waive that requirement.

Caine has served in positions including associate director for military affairs at the CIA as well as in various operational and staff roles, and flew more than 150 hours in combat as an F-16 pilot, an aircraft in which he logged more than 2,800 hours in total.

A military official who served with Caine said shortly after Trump announced his nomination that the retired general has "never been a partisan actor, always been apolitical and focused on just simply warfighting and whatever the mission success is."

Trump has described Caine as "an accomplished pilot, national security expert, successful entrepreneur, and a 'warfighter' with significant interagency and special operations experience."

The president apparently became enamored of Caine after meeting him in Iraq during his first term, where the general told Trump that his nickname was "Razin."

"I said, wait a minute, your name is Razin Caine? I love you, I've been looking for you for five years... this is what I want," Trump told an investor forum in February.

Trump abruptly fired Brown in February without explanation, leaving the vice chairman to lead the Joint Chiefs in an acting capacity.

In addition to him, top US Navy officer admiral Lisa Franchetti, the Air Force vice chief of staff and three senior military lawyers have also been sacked.

Hegseth has insisted the president is simply choosing the leaders he wants, but Democratic lawmakers have raised concerns about the potential politicization of the traditionally apolitical US military.