President Donald Trump has called the impeachment inquiry “total nonsense” and criticised US diplomats who gave evidence to Congress.

Mr Trump described the inquiry as a “hoax” and said Democrats in the House of Representatives looked like “fools” during the hearings.

He also talked up debunked conspiracy theories that Ukraine interfered in the 2016 election, speaking just one day after a former White House adviser told the hearings that the claim was a “fictional narrative” that played into the hands of Russian President Vladimir Putin.

Mr Trump also repeated claims that officials from former president Barack Obama’s administration spied on his campaign and underscored the need to keep Republicans unified against impeachment.

“I don’t think I’ve ever seen support in the Republican party like we do right now,” he said.

In a 57-minute, animated phone interview on cable news programme Fox & Friends, Mr Trump said he did not expect to be impeached. But he added that if the House did vote to impeach him, he would welcome a trial in the Republican-led Senate.

“Frankly, I want a trial,” he said.

A trial, he said, would give Republicans a chance to question representative Adam Schiff, who led the hearings as chairman of the House intelligence committee.

Procedures for a Senate trial are still being worked out, but Republicans may well be hesitant to adopt Mr Trump’s idea of turning a member of Congress into a witness.

“I want to see Adam Schiff testify about the whistleblower, who is a fake whistleblower,” the president said, adding that he knows the identity of the whistleblower whose formal complaint launched the impeachment inquiry.

Mr Trump’s professed confidence came after impeachment witnesses gave evidence under oath that the president withheld aid from Ukraine to press the country to investigate his political rivals.

Mr Trump insisted he was trying to root out corruption in the Eastern European nation when he held up nearly 400 million dollars in military aid to help Ukraine battle Russian aggression.

“I think it’s very hard to impeach you when they have absolutely nothing,” Mr Trump said.

He denied there was any quid pro quo, extortion or bribery. He also denied holding up a White House meeting or military aid to get Ukrainian President Volodymyr Zelenskiy to launch investigations of former vice president Joe Biden and his son’s dealings in Ukraine.

Uncowed by witnesses who warned against playing into the Russians’ hands, Mr Trump repeated a debunked conspiracy theory that Ukrainians might have hacked the Democratic National Committee’s network in 2016 and framed Russia for the crime.

Mr Trump said: “They gave the server to CrowdStrike, which is a company owned by a very wealthy Ukrainian. I still want to see that server. The FBI has never gotten that server.”

Mr Trump’s claim on Ukraine being behind the 2016 election interference has been discredited by intelligence agencies and his own advisers.

CrowdStrike, an internet security firm based in California, investigated the DNC hack in June 2016 and traced it to two groups of hackers connected to a Russian intelligence service — not Ukraine. The company’s co-founder Dmitri Alperovitch is a Russian-born US citizen who immigrated as a child and graduated from the Georgia Institute of Technology.

Fiona Hill, a former Russia adviser on the White House National Security Council, admonished Republicans in her evidence on Thursday for pushing unsubstantiated conspiracy theories about Ukrainian interference in the 2016 presidential election.

Trump Impeachment
The impeachment hearings this week heard from former White House national security aide Fiona Hill, centre, and US diplomat David Holmes, right (Manuel Balce Ceneta/AP)

“This is a fictional narrative that has been perpetrated and propagated by the Russian security services themselves,” Ms Hill said.

Mr Trump continued to distance himself from other impeachment witnesses, including Gordon Sondland, US ambassador to the European Union.

Mr Sondland said he was working on a deal to arrange a White House visit if Mr Zelenskiy publicly announced investigations into Burisma, a Ukrainian gas company. Democrat Joe Biden’s son Hunter was a Burisma board member.

Speaking of Mr Sondland, Mr Trump said: “I hardly know him, OK? I’ve spoken to him a few times.”

The president said Mr Sondland left out of his opening statement his account of a phone conversation in which Mr Trump said: “I want nothing. No quid pro quo. Have Zelenskiy do whatever is right.”

Mr Sondland “didn’t put that in,” Mr Trump said. “That was the end of him. I turned off the television.”

He also denigrated the evidence of David Holmes, a counsellor at the US embassy in Kiev. Mr Holmes said he overheard a different phone conversation Mr Sondland had with the president. Mr Holmes said he heard the president talking loudly about Mr Zelenskiy, asking, “So, he’s gonna do the investigation?” Mr Sondland replied that “he’s gonna do it”.

Mr Trump said he did not believe Mr Holmes could hear the conversation since it was not on a speaker phone.

And Mr Trump continued to disparage former US ambassador to Ukraine Marie Yovanovitch. He recalled her from her post in Kiev before her tenure was to end. Mr Trump called her an “Obama person” and claimed she did not want his picture to hang on the wall of the embassy.

Ian Kelly, the former US ambassador to Georgia, tweeted in Ms Yovanovitch’s defense, saying: “Our official White House portraits did not arrive at Embassy Tbilisi until March 2018. This was because the WH (White House) was late getting them to all embassies.”