US President Donald Trump has described moves to impeach him as the "most destructive witch hunt of all time" and he is pledging to release the transcript of a phone call that's at the centre of the brewing political storm.
Mr Trump has faced threats of impeachment before - but until now the Democrats have taken a a cautious approach.
But the House of Representatives is forging ahead with a formal inquiry after a whistle-blower alleged President Trump pressured the President of Ukraine to dig dirt on Democratic rival Joe Biden and Biden's son.
CNN's Whitney Wild explains why the gloves are suddenly off.
