Three House committees have released dozens of texts between U.S. diplomats in Ukraine discussing how to handle a response to President Donald Trump's demands that the country launch an investigation into Joe Biden's family.

The release follows an almost 10-hour interview with former Ukrainian envoy Kurt Volker. Volker provided the text messages to the committees.

In the texts, Volker and two other diplomats discuss how to navigate Trump's requests for the probe into his political rival.

In one exchange, Volker and Ambassador Gordon Sondland discussed a draft statement in which the Ukraine government would announce an investigation into the 2016 U.S. presidential election and into a company whose board Biden's son served on.

Trump's pressure on Ukrainian President Volodymyr Zelenskiy is the subject of the House Democrats' impeachment investigation.

The former special U.S. envoy to Ukraine testified Thursday of turmoil within the State Department over President Donald Trump's push to investigate Joe Biden and his family, placing Rudy Giuliani at the center of the effort.

Kurt Volker, a central figure in the House's impeachment inquiry, appeared for nearly 10 hours behind closed doors. He told lawmakers he was never pressured by Trump or others around the administration to have Ukraine conduct the investigation of the Democratic rival, and in fact said he had warned Ukrainians to steer clear of American politics.

Yet Volker also recalled being told that plans for a meeting between Trump and the new Ukrainian president elected in the spring were being put on ice, according to one person familiar with the private meeting who, like others, spoke on the condition of anonymity to discuss it.