WASHINGTON - US President Donald Trump on Tuesday denounced the impeachment inquiry threatening his presidency as a "coup", as his administration pushed back hard against the investigation.
Trump's comments came after his Secretary of State Mike Pompeo vowed to prevent or delay five State Department officials from testifying in the investigation probing accusations that Trump abused his office by seeking dirt from Ukraine on a 2020 election rival.
"As I learn more and more each day, I am coming to the conclusion that what is taking place is not an impeachment, it is a COUP," Trump tweeted.
It is "intended to take away the Power of the People, their VOTE, their Freedoms, their Second Amendment, Religion, Military, Border Wall, and their God-given rights."
Pompeo meanwhile accused the three Democratic heads of the House of Representative committees conducting the impeachment inquiry of "an attempt to intimidate, bully and treat improperly the distinguished professionals of the Department of State".
But Democrats accused the top US diplomat of "stonewalling" the investigation and, according to media reports, scheduled interviews with at least two of the diplomats who both had direct involvement in the Ukraine matter.
It was the first major clash in the days-old impeachment probe, pointing to a dramatically mounting political and legal siege as Trump battles to save his presidency.
Democrats decided last week to seek impeachment after a whistleblower complaint, supported by a White House call transcript, showed Trump pressuring Ukrainian President Volodymyr Zelenskiy to supply him with politically useful information on Democratic former vice-president Joe Biden. Biden is the most likely Democrat to challenge Trump's reelection bid next year.
The first move of the three powerful House Democrats - Adam Schiff of the Intelligence Committee, Eliot Engel of the House Foreign Affairs Committee and Elijah Cummings of the Oversight Committee - was to subpoena Pompeo and Trump's private lawyer Rudy Giuliani for documents and to summon the five diplomats to testify.
Pompeo suggested that the committees could be forced to subpoena the five officials, and that the State Department and White House could seek to limit what they can talk about.
"I will use all means at my disposal to prevent and expose any attempts to intimidate the dedicated professionals whom I am proud to lead," Pompeo said.
But news reports said the State Department's former special envoy to Ukraine, Kurt Volker, would testify on Thursday and that the ex-ambassador to Kiev, Marie Yovanovitch, would appear behind closed doors on Oct 11.
Volker had been sought by Giuliani to help pressure Zelenskiy, while Yovanovitch was removed earlier this year as ambassador after she reportedly resisted that effort.