The fourth impeachment inquiry of a president in U.S. history moves from behind closed doors into public view Wednesday as the House Intelligence Committee holds its first televised hearing in its probe into President Trump and his interactions with Ukraine.

The first witnesses to testify this week are three career diplomats — William B. Taylor Jr., acting ambassador to Ukraine; George Kent, deputy assistant secretary of state for European and Eurasian affairs; and Marie “Masha” Yovanovitch, former U.S. ambassador to Ukraine. Taylor and Kent will appear together Wednesday and Yovanovitch will testify Friday.

All three previously gave depositions to House investigators, and their transcripts were made public last week.

The panel of 22 House members, 13 Democrats and 9 Republicans, will convene in Room 1100 of the Longworth House Office Building. The large, first-floor committee room served as the temporary House chamber in 1949 and 1950 during reconstruction of the chamber in the Capitol building.

Doors will open to the public at 9:45 a.m., and Chairman Adam B. Schiff (D-Calif.) will gavel in the proceedings at 10 a.m. Wednesday.

Both Schiff and ranking Republican Devin Nunes (Calif.) will give opening statements. Schiff will then swear in the witnesses and invite Taylor and Kent to give their opening remarks.

The lawyers on the committee for the Democrats and for the Republicans will be given 45 minutes each to question the witnesses. Only Schiff and Nunes can participate in this round.

Following this portion of the hearing, the rest of the committee members will be given five minutes each to ask questions, alternating between majority and minority.

The Republicans last week swapped out committee member Rep. Eric A. “Rick” Crawford (R-Ark.) for Rep. Jim Jordan (Ohio), a close ally of Trump, who is expected to go hard in his defense of the president.

Schiff has attempted to preempt Republicans’ efforts to divert the conversation from Trump by limiting the scope of the hearing to three specific questions related to whether the president asked a foreign leader to investigate a political opponent, used his presidential power to apply pressure on a foreign government to help him politically, and whether he or his aides sought to conceal that behavior from Congress and the American people.