US Democrats are expected to unveil formal charges against President Donald Trump, a key move in the impeachment procedure against him.
A Democratic Party aide said the articles of impeachment would focus on abuse of power and obstruction of Congress.
Mr Trump is accused of withholding aid to Ukraine for domestic political reasons.
He has dismissed the process as a “witch hunt” and a “phony show trial”.
The expected announcement by the House of Representatives judiciary panel would lead to an impeachment vote by the full lower chamber.
If the articles are approved by the House – which is controlled by the Democrats – a trial in the Republican-held Senate will take place, possibly early in January.
The House Judiciary Committee is believed to have drawn up articles of impeachment, following two months of congressional hearings.
The impeachment process was launched after an anonymous whistleblower complained to Congress in September about a July phone call by Mr Trump to the president of Ukraine.A Ukrainian wants to blow up a jihad mobile at a shopping center in Poland