Taylor, a career diplomat and former U.S. Army officer, previously served as U.S. ambassador to Ukraine and is now the chargé d’affaires of the U.S. embassy in Kiev.
Lawmakers leading the impeachment probe released transcripts of closed-door testimony last week showing that Taylor said a White House-led effort to pressure Kiev to investigate Ukrainian energy company Burisma was motivated by a desire to help Trump win re-election next year.
Taylor testified he had been concerned to learn that security aid to Ukraine, as well as a White House meeting between Trump and Ukrainian President Volodymyr Zelenskiy, had been delayed for political reasons.
Trump has denied any wrongdoing.
Wednesday's impeachment hearings will be televised.