Trump impeachment inquiry enters new phase

The Democrat-led US House of Representatives is set to reach a turning point in its probe into whether President Donald Trump inappropriately pressed the government of Ukraine to intervene in US politics, passing from an investigative phase to deciding whether Trump should be impeached.

With the president abroad at the NATO meetings in London, the shift marks a perilous moment in his troubled presidency after the release on Tuesday of a 300-page report by House Intelligence Committee investigators describing Trump's months-long effort to pressure Ukraine.

The report circulated by the House Intelligence Committee, together with the Foreign Affairs and Oversight committees, alleges Trump "subverted US foreign policy toward Ukraine" and "undermined" US national security by seeking two politically motivated investigations to "help his presidential re-election campaign".

It also accuses Trump and his lawyers of obstructing the House impeachment investigation.

In a landmark hearing on Wednesday, four constitutional law scholars will discuss whether the case against Trump meets a political and legal test for impeachment.

"The big issue facing the Judiciary Committee is, what constitutes an impeachable offence," said Melissa Murray, a professor of law at the New York University law school.