A top US diplomat told impeachment hearings that President Trump directly asked about a Ukrainian investigation into his Democratic rival Joe Biden.
In previously unheard testimony, Bill Taylor, the acting US ambassador to Ukraine, said a member of his staff was told Mr Trump was preoccupied with pushing for a probe into Mr Biden.
He was speaking at the first public hearings in the impeachment inquiry.
Mr Trump told reporters he did not recall making such comments.
Mr Trump is accused of withholding US military aid to Ukraine in order to pressure the country’s new president to publicly announce a corruption inquiry into Mr Biden, among the favourites to take him on in the 2020 presidential race.
Mr Trump denies any wrongdoing and has called the inquiry a “witchhunt”.