Congress has invited US President Donald Trump to its first impeachment hearing on 4 December.
The democratic chairman of the house judiciary committee, Jerrold Nadler, said Mr Trump could either attend or “stop complaining about the process”.
In his letter to the President, Mr Nadler said the hearing would be an opportunity to discuss the historical and constitutional basis for impeachment.
He has given Mr Trump until 23:00 GMT on 1 December to confirm whether or not he will be at the hearing, and if so, to let the committee know who his counsel will be.
It would mark the next stage in the impeachment inquiry, which centres on a July phone call between Mr Trump and Ukrainian president Volodymyr Zelensky.
Last week, the house intelligence committee wrapped up two weeks of public hearings, which followed several weeks of closed-door witness interviews.
The judiciary committee is expected to begin drafting articles of impeachment – which are the charges of wrongdoing against the President – in early December.
After a vote in the democratic-controlled house, a trial would be held in the republican-run senate.
If Mr Trump was convicted by a two-thirds majority – he would become the first us president to be removed from office through impeachment.