Trump says impeachment inquiry a 'joke' as whistleblower complaint voted to be released

The whistleblower complaint has now been reviewed by lawmakers and was voted to be released

A downbeat Donald Trump on Wednesday dismissed as a "joke" the grounds laid out for the impeachment inquiry into him, as Democrats stood firm in accusing the US president of a "mafia-style shakedown" of his Ukrainian counterpart.

Trump denied claims he abused his office by repeatedly urging President Volodymyr Zelensky to probe his rival Joe Biden -- as confirmed in a call transcript released by the White House.

The next explosive episode in the rapidly unfolding impeachment drama is set for Thursday, when acting director of national intelligence Joseph McGuire testifies on Capitol Hill.

"They are getting hit hard on this witch hunt because when they look at the information, it's a joke," said the president, who struck an uncharacteristically subdued tone at his first news conference since Democrats launched an official impeachment inquiry.

The publication of the transcript sent new shockwaves through Washington, including within the ranks of Trump's Republican Party, with Senator Mitt Romney calling it "deeply troubling."

In announcing the impeachment probe, House Speaker Nancy Pelosi said Trump's actions amounted to a betrayal of his oath of office and of national security.

Democrats made clear the White House's release of the call record would not satisfy their investigation into whether the US leader broke the law, and the complaint has now been reviewed by lawmakers.

Top Democratic Senator Chuck Schumer told reporters after reading the whistleblower complaint that "it's very troubling" -- an assessment echoed by Republican Senator Ben Sasse, who said that "there's obviously lots that's very troubling there."

Schumer later called in a statement for the contents of the complaint to be made public, saying: "The public has a right to read the whistleblower's complaint for themselves."