NATIONWIDE — Two State Department officials are publicly testifying as part of the impeachment inquiry into President Donald Trump.

House Democrats are expected to use career State Department officials to argue that Trump violated his oath of office by pushing Ukraine's president to investigate political rivals while withholding military funds.

The two key witnesses answering questions publicly Wednesday are George Kent, a senior State Department official in charge of Ukraine policy, and Bill Taylor, the top U.S. diplomat in Ukraine.

Both have testified previously behind closed doors. They both testified there was a demand from the Trump administration that Ukraine investigate former Vice President Joe Biden in exchange for receiving $400 million in military aid.

Republicans argue the money was given to Ukraine without any investigation and there was no quid pro quo.

Expect both Republican and Democratic lawmakers to use their lines of questioning to set up their positions.

Intelligence Committee Chairman Adam Schiff and Republican ranking-member U.S. Rep. Devin Nunez will have up to 45 minutes to question witnesses at each hearing. Rank-and-file lawmakers will get five minutes.

This is only the fourth time in more than two centuries that there has been an impeachment effort.

LIVE UPDATES: Diplomats Publicly Questioned in Trump's Impeachment Inquiry