Hillary Clinton has joined the growing number of Democrats who are calling for an impeachment investigation to begin into President Donald Trump.

Clinton, who has been a critic of Trump since she ran for the Presidency in the 2016 election, said that now feels like the right time to begin proceedings.

It comes after reports President Trump pressured Ukraine's government to look into the family of his leading 2020 challenger, Vice President Joe Biden, and whether the former Vice President had pulled strings to get his son into the country.

'We are in a crisis,' Clinton said to People. 'I did not come to that decision easily or quickly but this is an emergency as I see it. … This latest behavior around Ukraine, trying to enlist the president of Ukraine in a plot to undermine former Vice President Biden or lose the military aid he needs to defend against Trump's friend, Vladimir Putin — if that's not an impeachable offense, I don't know what is.'

Former Secretary of State Hillary Clinton announced Tuesday that she supports impeaching President Donald Trump

President Trump has insisted that he's done nothing wrong when it comes to Ukraine or was seeking an investigation into Biden's son's dealings

Mrs Clinton calls the president 'a reckless, corrupt human tornado'

President Trump claims he stopped financial support for Ukraine which had been approved by Congress, before he spoke with Ukraine's president about Biden and Biden's son Hunter.

Trump has said the two issues were not related.

He has accused Joe and Hunter Biden and Hunter of 'corruption', although so far has not provided any evidence.

Trump has denied any wrongdoing, saying his call with Ukraine's president was not improper.

He has dismissed criticism that he used his power as president for blatant electioneering as a 'witch hunt.'

Clinton has called Trump 'a reckless, corrupt human tornado who cares only about himself.'

President Trump has accused Hunter, left, and Joe Biden of 'corruption', although so far has not provided any evidence

She told People that it was the constitutional duty of the House of Representatives to begin impeachment proceedings 'not happily or with glee, but in the interests of national security.'

'The president of the United States is betraying our country on a daily basis,' she said.

'This man who is in the Oval Office right now is a clear and present danger to the future of the United States.'