United States Democratic lawmakers have demanded documents from the White House as part of their impeachment inquiry into the nation’s president, Donald Trump.
The documents relate to a call between Mr Trump and Ukrainian President Volodymyr Zelensky on 25 July.
In the call, Mr Trump pushed Mr Zelensky to investigate his leading Democratic political rival, Joe Biden.
The impeachment inquiry stems from the call, which was flagged up by a whistleblower in August.
The US president has denied any wrongdoing, accusing his political opponents of a “witch hunt”.
But in a move to crank up the pressure on the president, the three House committees leading the investigation have given him until 18 October to hand over the documents.
“We deeply regret that President Trump has put us – and the nation – in this position, but his actions have left us with no choice but to issue this subpoena,” the Democrats wrote in a letter to the White House.
The subpoena an order to hand-over evidence was issued on Friday by the chairmen of the committees for Oversight, Intelligence and Foreign Affairs.
White House press secretary Stephanie Grisham according to BBC sought to play down the subpoena, saying it “changes nothing”.
A separate request for records has also been sent to Vice-President Mike Pence, with Democrats asking him to clarify “any role you may have played” in Mr Trump’s overtures to Ukraine.
If Democrats manage to impeach the president by way of a vote in the House of Representatives – a trial would be held in the Senate, BBC reported.
Senators would have to vote to convict Mr Trump by a two-thirds majority to remove him from office.
But that outcome is seen as unlikely given that the president’s fellow Republicans control the Senate.
In their letter to the White House, the committees accused Mr Trump of “stonewalling” multiple requests for records relating to his July 25 call with Mr Zelensky.
By refusing to voluntarily release the documents, the Democrats said Mr Trump had “chosen the path of defiance, obstruction, and cover-up”.
Failure to comply with the subpoena would amount to “evidence of obstruction”, which is also an impeachable offence, the committees warned.