The BBC has obtained leaked emails that show a lobbying effort to get US Secretary of State Rex Tillerson sacked for failing to support the United Arab Emirates against regional rival Qatar.
Major Trump fundraiser and UAE-linked businessman Elliott Broidy met US President Donald Trump in October 2017 and urged him to sack Mr Tillerson, the emails reveal.
In other emails, he calls the top US diplomat "a tower of Jello", "weak" and says he "needs to be slammed".
Mr Broidy says Qatar hacked his emails.
"We have reason to believe this hack was sponsored and carried out by registered and unregistered agents of Qatar seeking to punish Mr Broidy for his strong opposition to state-sponsored terrorism," a spokesman for the businessman said.
He said some of the emails "may have been altered" but did not elaborate.
Saudi Arabia, UAE and a number of Arab countries cut diplomatic ties with Qatar in June 2017 over its alleged support for terrorism, a claim which it denies. The unprecedented move was seen as a major split between powerful Gulf countries, who are also close US allies.
Qatari officials denied the claims in a statement to the BBC.
Its communications office said: "Qatar would like to state unequivocally that it has not engaged in or committed any of the alleged accusations made falsely by Mr Broidy, nor has it engaged or paid anyone to do so.
"We believe that Mr Broidy's baseless accusations are simply a diversionary tactic to distract attention from the serious allegations against himself and his client the Government of the United Arab Emirates.
"The Government of Qatar reserves its right to taking any necessary legal action as the victim of false allegations by Mr Broidy or others."
Mr Broidy's defence company Circinus has hundreds of millions of dollars worth of contracts with the UAE, according to the New York Times newspaper.
He had recently returned from the UAE when he met Mr Trump at the White House in October.
What did the emails say?
According to a memorandum he prepared of the meeting, Mr Broidy urged continued support of US allies the UAE and Saudi Arabia and advised Mr Trump against getting involved in last year's row with Qatar.
Mr Broidy called Qatar "a television station with a country" - alluding to broadcaster Al Jazeera - and said it was doing "nothing positive", according to the emails.
He said he touted a regional counter-terrorism force being set up by the UAE that his company was involved with, and suggested that the US president "sit down" with Mohammed bin Zayed al-Nahyan, the crown prince of Abu Dhabi and a top UAE military commander.
"I offered that MBZ [the crown prince] is available to come to the US very soon and preferred a quiet meeting in New York or New Jersey. President Trump agreed that a meeting with MBZ was a good idea," Mr Broidy wrote in an email.
He also said he advised the president on Mr Tillerson - who was "performing poorly and should be fired at a politically convenient time".
Mr Tillerson had criticised the blockade of Qatar and called for it to be eased, in comments that contrasted with Mr Trump's support for the move.
Mr Tillerson spent most of the first year in his position embattled and weakened.
Last autumn, in a rare move for the soft-spoken secretary, the state department held a press conference in which Mr Tillerson pushed back against reports he had called the president "a moron".
Who did Mr Broidy email?
He emailed a detailed account of his meeting with the president to George Nader, a Lebanese-American businessman with decades of experience serving as an interlocutor between the Middle East and Washington.
Sources familiar with the investigation of Special Counsel Robert Mueller, who is looking into alleged Russian meddling in the 2016 US election and possible links between the Trump campaign and the Kremlin, tell the BBC that Mr Nader has become a person of interest and has been questioned in recent weeks.
Investigators questioned Mr Nader and other witnesses on whether there were any efforts by the Emiratis to buy political influence by directing money to Mr Trump's presidential campaign, according to a New York Times report.
What else was in the leaked emails?
Mr Broidy also detailed a separate sit-down with Mr Trump's son-in-law and adviser Jared Kushner, according to the emails.
After Mr Broidy criticised Qatar extensively to Mr Kushner, "Jared's demeanour was very passive and pleasant but he seemed to not want to engage on this issue," he wrote to Mr Nader.
However, Mr Kushner has maintained that he has had no role in his family's business since joining the White House last year.
Has anyone else claimed to have been hacked?
UAE ambassador to Washington Yousef al-Otaiba - who in diplomatic circles is known as the most effective and influential ambassador in Washington - has himself been a recent victim of email hacking.
It's well known in Washington that Mr Otaiba and Mr Kushner have enjoyed a close relationship.
Industry experts looking at both hacks have drawn comparisons between the two, showing reason to suspect links to Qatar.
"This is rinse and repeat on Otaiba," a source familiar with the hack told the BBC.