Four investigations Democrats could launch if they win Congress

Democrats have made it clear that lucrative deals brokered by the Trump family's vast business empire will be primary targets of any initial investigations.

"We want to make sure that [American] taxpayer dollars are being used wisely and not being stolen or pocketed because of corruption," Virginia Democratic Representative Suhas Subramanyam, a member of the House Oversight Committee, told the BBC.

Items under consideration for investigation include ties between the administration and corporate entities - particularly cryptocurrency firms - as well as the international business dealings of the president's son-in-law, Jared Kushner.

Other topics could include the $400m (£301m) aircraft gifted by Qatar to serve as Air Force One and multimillion-dollar defence contracts awarded to firms linked to the Trump family.

"What's shocking to me is not only that this administration, cabinet officials and even the president and his family have been corrupt and self-dealing, but they've been so brazen and open about it," Subramanyam said.

The White House has repeatedly denied any allegations of wrongdoing.

"President Trump is focused on retaining Republican majorities in Congress and doubling down on the progress he has made to lower costs for families," White House spokesperson Olivia Wales said.

"Democrats have no agenda to improve the lives of the American people, just plans to obstruct and baselessly target President Trump's commonsense agenda," she added.

A White House official said the administration is "always prepared" to respond to oversight requests regardless of who is in Congress.

Some experts believe that the negative publicity that would come from congressional hearings could ultimately lead to Hegseth being fired or resigning from the position.

"[If] it looks bad for the White House, and it's a drag on their media attention, President Trump might be likely to cut loose those officials, because he doesn't want that bad press," said David Miller, a political science professor and expert on the presidency at American University in Washington DC. "In a sense that could be a win for the Democrats."

Richard Painter, the former chief White House ethics lawyer under George W Bush, told the BBC that the decision to launch the war should come under scrutiny.

"The bigger issue is this: this war was never authorised by the United States Congress, and I don't care who the secretary of defence is," he said.

"The constitution says that Congress declares war," he said, and lawmakers should "haul these folks in" to answer questions.

In a statement, Pentagon Press Secretary Kingsley Wilson defended Hegseth's record, calling him a "transformative leader" who has "slashed bureaucracy, unleashed innovation, and delivered for our warfighters".

"By every measurable metric, the Department of War is better under Secretary Hegseth's leadership than before," she said, using the administration's preferred name for the defence department.

Democrats are split on the possibility of attempting to impeach Trump for a third time.

Some, such as Representative Alexandria Ocasio-Cortez, have expressed support for an impeachment, citing what they view as an unauthorised war with Iran and other alleged impeachable offences.

Others have called for a more cautious approach, arguing that any impeachment is unlikely to end in the Senate voting to remove Trump - who has repeatedly denied any wrongdoing - from office.

It is also unclear whether the party could agree on a reason to launch impeachment proceedings.

"I can do whatever I want, if I want," Trump told reporters in the Oval Office in October, adding that he sees the impeachment efforts in his first term and the later criminal cases brought against him as "very illegal things".

James Comer, the Republican chairman of the House Oversight Committee, told the Washington Sun news outlet in June that Democrats were "one-trick ponies" who were "going to go after Trump".

There is no guarantee for Democrats that any potential investigation would end with a meaningful outcome.

But Subramanyam said their efforts would send a message.

"If we do not do something because we are scared of the optics, or we don't think it will be successful, or they stonewall us, that will be bad," he said. "Not just for the next two years, but for the next 20 years."