Donald Trump has called Democratic congresswoman Rashida Tlaib a "despicable human being" after she revealed discussions about jailing White House officials who seek to obstruct the impeachment inquiry by refusing to testify.
Ms Tlaib, a member of the self-styled "Squad" of progressive first-term congresswomen, told Deadline Detroit that Democrats had talked about arresting allies of the president who refuse to comply with subpoenas to give evidence to Congress.
The White House has said it will not co-operate with the impeachment inquiry, which was launched amid fears that Mr Trump was abusing his office by trying to get a foreign leader to dig up or even manufacture dirt on one of his leading political opponents, Joe Biden.
Last week Gordon Sondland, the US ambassador to the European Union, refused to testify after being told not to by the State Department.
However, he is expected to do so on Monday, three days after the former Ukraine ambassador, Marie Yovanovitch, ignored a State Department instruction not to testify and gave evidence for several hours to Congress.
The president retweeted a comment about the story by Dan Scavino, the White House social media director, which read: "Sounds about right. COUP!"
Mr Trump added his own comment: "A despicable human being!"
In July he said they should "go back" to the countries they came from rather than "loudly and viciously telling the people of the United States" how to run the government. Three of the four were born in the United States and all of them are US citizens.
The next month Mr Trump put pressure on the Israeli prime minister Benjamin Netanyahu to block Ms Tlaib and Ms Omar from entering the country because of their support for the movement to boycott Israeli goods.
Ms Tlaib was later given permission to visit her grandmother in the West Bank but only on condition that she agreed not to promote boycotts while there, a condition she refused.
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