Trade negotiators from Beijing are set to travel to Washington next week for a round of high-level talks aimed at bringing about a resolution to the trade war that has raged between the two countries since July 2018.

Trump’s appeal to Beijing came as his administration scrambled to fight back against an impeachment inquiry launched by House Democrats into whether Trump asked Ukraine to investigate Hunter Biden’s business dealings in the country in exchange for US military aid.

Trump and his allies have accused Joe Biden, during his time as Obama’s vice-president, of pressuring Ukraine to fire a prosecutor to help diffuse scrutiny of his son’s link to a Ukrainian energy company that was under fire for corruption.

There is no evidence of wrongdoing on the part of either Joe Biden or his son, and Biden was not alone in calling for the prosecutor's firing. CNN reported on Thursday that several senior Republican lawmakers had also expressed concerns about corruption inside the prosecutor's office.

Democrats, meanwhile, accuse Trump of soliciting a foreign power to dig up “dirt” on a political opponent and of attempting to cover up the conversations, after a whistle-blower’s complaint alleged that records of a call with Ukrainian president Volodymyr Zelensky were buried in a White House server reserved for classified material.

Yet despite the growing crisis engulfing the White House, Trump on Thursday not only repeated his call to the Ukrainian government to investigate the Bidens but also looped in Beijing in a winding response to reporters.

“[Ukraine] should investigate the Bidens, because how does a company that’s newly formed, and all these companies if you look at – and, by the way, likewise China should start an investigation into the Bidens,” Trump said outside the White House.

“What happened in China is just about as bad as what happened with Ukraine,” he said, accusing the Bidens of “scamming China”.

Trump accused Beijing of paying “billions of dollars” in “payoffs” to the Bidens, in exchange for beneficial treatment by the US on matters of trade.

“And that’s probably why China for so many years has had a sweetheart deal where China rips off the USA,” Trump said. “Because they deal [with] people [like] Biden, where they give the son a billion and a half dollars.”

Trump says Biden’s son ‘walks out of China with US$1.5 billion’

The figure of US$1.5 billion appeared to be referring to the amount that a private equity fund, founded in 2013 and on whose advisory board Hunter Biden sat, had aimed to raise. Hunter Biden did not take an equity stake in the fund, called BHR Partners, until after his father left office, according to The New Yorker.

Allegations of impropriety grew after it emerged that in 2013 Hunter Biden joined his father on Air Force Two, the vice-president’s official plane, to China, where Biden was to meet Xi Jinping.

During the trip, the two met with a business associate of Hunter Biden’s, leading to criticism that he was harnessing his proximity to the heart of US politics to gain traction in his business ventures.

The CNN report did not say whether Trump asked in his June phone call with Xi for an investigation of the Bidens when he brought up the subject of the former vice president and Warren.

The Chinese embassy in Washington did not respond to a request for comment on Trump’s remarks.

Scrutiny over Hunter Biden’s dealings in China has only grown since his father launched his bid for the Oval Office.

Senator wants US inquiry into deal between Chinese company and Biden’s son

Trump’s call on China to investigate a political opponent was met with outrage from Democrats, while David Adelman, a former US ambassador, described the request as “wildly outside the norms of international diplomacy”.

Sharing a video on Twitter of Trump’s appeal to the Ukrainian and Chinese governments, Hillary Clinton, who lost to Trump in the 2016 presidential election, said: “Someone should inform the president that impeachable offences committed on national television still count.”

“Russia. Ukraine. China. How far will Trump really go to sell out America’s sovereignty to stay in office?” Maryland Senator Chris Van Hollen tweeted.

Just before his call on China to investigate the Bidens, Trump said of the current trade dispute: “I have a lot of options on China, but if they don’t do what we want, we have tremendous, tremendous power.”

Trump allies play defence as Democrats move on impeachment

Adelman, who served as former president Barack Obama’s envoy to Singapore from 2010 to 2013, said Beijing would be “highly unlikely to engage in anything that would impact US domestic politics”, and would not jump on the invitation for the sake of leverage in looming trade talks.

“Leaders in Beijing will view this for what it is,” said the former diplomat, “which is part of the political rhetoric in the heat of the moment during a time when the president is under intense domestic political pressure.”

Warren seized on the CNN report that Trump agreed to keep quiet about the anti-government demonstrations in Hong Kong, calling it a “sell out” of Hongkongers “behind closed doors”.

Trump came under criticism earlier this week for congratulating Xi on the 70th Anniversary of the People’s Republic of China without mentioning the police shooting of an anti-government protester in Hong Kong, which had occurred a few hours earlier.

Many Republican and Democratic lawmakers discussing China afterwards criticised Beijing, blaming the government for more than four months of unrest in the city, repression of China’s ethnic Uygur population and other contentious issues.

Additional reporting by Robert Delaney