DONALD Trump has condemned “corrupt” Democrats and the whistleblower behind the congressional impeachment inquiry, accusing them of pursuing a “deranged witch hunt”.

The US president was addressing a crowd in Louisiana as Democrats prepared for the first public hearings next week in the probe into a whistleblower’s claims about a call Trump held with the Ukrainian president.

Trump said: “Democrats must be accountable for their hoaxes and their crimes.

“Now corrupt politicians Nancy Pelosi and shifty Adam Schiff and the crooked media have launched the deranged, delusional, destructive and hyper-partisan impeachment witch hunt.

“But the whistleblower came out with his horrible statement about this call. So I really had no choice. I said immediately – talk about transparency – I said: ‘Release it. Release it immediately’.

“And then the whistleblower saw it, and shifty Schiff saw it, who is a total crook. Schiff saw it. Pelosi saw it. And they said, ‘We’ve got a problem. We don’t want to have anything to do with the whistleblower any more’. And the whistleblower disappeared.”

The president was in Louisiana to boost Republican businessman Eddie Rispone’s effort to unseat Democratic governor John Bel Edwards in the nation’s last governorship race of the year.

“It may be 120 degrees in this room,” Trump told the crowd at the end of the rally in the city of Monroe.

“Somebody is saving on air conditioning,” he joked. “That’s all right. You’ve always got to save a little money.”

The run-off election offers the president an opportunity to pick up a win in a rare Democratic-held governor’s seat in the Deep South and change the narrative after a pair of apparent setbacks this week for Republicans in Kentucky and Virginia.

“The American people are fed up with Democrat lies, hoaxes, smears, slanders and scams. The Democrats’ shameful conduct has created an angry majority. And that’s what we are,” Trump said.

“We’re a majority, and we’re angry, that will vote the do-nothing Democrats out of office in 2020.”

Democrats have announced they will launch public impeachment hearings next week, intending to bring to life weeks of closed-door evidence and lay out a convincing narrative of presidential misconduct.

First to give evidence will be William Taylor, the senior diplomat in Ukraine, who has relayed in private his understanding that there was a blatant quid pro quo with Trump holding up military aid to a US ally facing threats from its giant neighbour Russia.

That aid, at the heart of the impeachment inquiry, is alleged to have been held hostage until Ukraine agreed to investigate Trump’s political foe Joe Biden.

The president has denied any wrongdoing and Republicans largely dismiss the impeachment inquiry, now into its second month, as a sham.

But Democratic representative Schiff, the chairman of the Intelligence Committee leading the probe, said that with two days of hearings next week Americans will have a chance to decide for themselves.