Trump news – live: Pentagon official set to testify in impeachment probe, as Biden extends poll lead over 2020 Democrat rivals

Donald Trump continues to froth over the impeachment inquiry on Twitter as Laura Cooper, deputy assistant US secretary of defence for Russia, Ukraine and Eurasia, becomes the latest senior official to appear before the House panel on Capitol Hill to testify about the conduct of diplomatic relations with Ukraine.

On Tuesday, Bill Taylor, acting US ambassador to Ukraine, told the inquiry he was informed military aid to the country was “dependent” on president Volodymyr Zelensky agreeing to publicly announce a corruption probe into Donald Trump’s 2020 rival Joe Biden, confirming the existence of the suspected quid pro quo at the heart of the Democratic-led investigation.

Mr Biden’s polling lead in the Democratic 2020 primary race is meanwhile at its widest margin since April. The former vice president has won the support of 34 per cent of voters registered with the party, according to a new CNN survey.

Please allow a moment for our live blog to load