WASHINGTON — Reeling from a Democratic impeachment investigation and rebellion in his own Republican Party, President Donald Trump retreated on Thursday to his comfort zone: the 2020 reelection campaign trail.

Trump left the White House for Minneapolis where he was due to gather with his ferociously devoted core supporters at the basketball arena. The president told reporters that images showing thousands lined up outside ahead of his arrival were "amazing."

The Minnesota city is a liberal bastion in the American heartland, giving Trump a juicy target for his favored rhetoric about a supposed far-left takeover of the US.

Leftist Somali-American congresswoman Ilhan Omar represents Minneapolis and Trump, who has made Omar a kind of bogey figure among his right-wing supporters, is likely to tear into her.

On Friday, he will take the "Make America Great Again" show to Louisiana.

The focus on reelection in 2020 provides a respite for Trump after a turbulent two weeks.

Democrats who have been accusing Trump of abusing his office throughout his first term believe they are finally cornering the president with an impeachment probe into his dealings with Ukraine.

Trump allegedly pressured new Ukrainian President Volodymr Zelensky to restart a dormant, largely discredited corruption probe of Joe Biden, the leading Democratic candidate to take on Trump next year.

The president has pushed back hard – refusing to cooperate with the impeachment inquiry – and seeking to turn the entire scandal into a boost for his reelection campaign.

But public support for impeachment is slowly growing, with a new poll from Fox News – a channel favored by US conservatives – showing 51 per cent now back his removal from office.

With control of the lower house of Congress, Democrats are likely to impeach in the coming months, even if few believe the Republican-led Senate will actually convict Trump and force him from office.

Trump argues that his now infamous July 25 phone call with Zelensky did not feature any kind of pressure, but an innocent proposal for pursuing corruption.

He got a boost on Thursday when Zelensky backed his version of events, telling journalists "there was no blackmail."

Democrats argue that given the vast power differential between the two leaders, Trump did not need to make explicit threats and that his request to Zelensky for "a favor" was enough. — AFP