The Latest on the public impeachment hearings into President Donald Trump’s dealings with Ukraine (all times local):

8:47 a.m.

Key impeachment witnesses Army Lt. Col. Alexander Vindman and adviser Jennifer Williams have arrived for their testimony at a House intelligence panel hearing. They are the Tuesday morning witnesses in a critical week of public hearings against President Donald Trump.

Lt. Col. Alexander Vindman arrives to testify before the House Intelligence Committee on Capitol Hill in Washington, Tuesday, Nov. 19, 2019, during a public impeachment hearing of President Donald Trump's efforts to tie U.S. aid for Ukraine to investigations of his political opponents. (AP PhotoJulio Cortez)

Lt. Col. Alexander Vindman arrives to testify before the House Intelligence Committee on Capitol Hill in Washington, Tuesday, Nov. 19, 2019, during a public impeachment hearing of President Donald Trump's efforts to tie U.S. aid for Ukraine to investigations of his political opponents. (AP PhotoJulio Cortez)

Vindman was wearing his dress uniform. Both Vindman and Williams, a State department employee deployed to Vice President Mike Pence’s staff, listened in on the key July 25 call between Trump and the Ukrainian president.

On the call, Trump prodded the Ukraine leader to do him the a “favor” and launch an investigation into Joe Biden and his son while crucial aid to Ukraine was being held up on his orders.

12:05 a.m.

Jennifer Williams, an aide to Vice President Mike Pence, arrives to testify before the House Intelligence Committee on Capitol Hill in Washington, Tuesday, Nov. 19, 2019, during a public impeachment hearing of President Donald Trump's efforts to tie U.S. aid for Ukraine to investigations of his political opponents. (AP PhotoJulio Cortez)

Jennifer Williams, an aide to Vice President Mike Pence, arrives to testify before the House Intelligence Committee on Capitol Hill in Washington, Tuesday, Nov. 19, 2019, during a public impeachment hearing of President Donald Trump's efforts to tie U.S. aid for Ukraine to investigations of his political opponents. (AP PhotoJulio Cortez)

Two top national security aides who listened to President Donald Trump’s call with Ukraine are scheduled to testify in the impeachment hearings, launching back-to-back sessions as Americans hear from those closest to the White House.

An Army officer at the National Security Council, Lt. Col. Alexander Vindman, and his counterpart at Vice President Mike Pence’s office, Jennifer Williams, both had concerns as Trump spoke on July 25 with the newly elected Ukraine president about political investigations into Joe Biden.

They are set to testify publicly Tuesday morning. In the afternoon, the House will hear from former NSC official Timothy Morrison and the former Ukraine special envoy, Kurt Volker.

Lt. Col. Alexander Vindman arrives to testify before the House Intelligence Committee on Capitol Hill in Washington, Tuesday, Nov. 19, 2019, during a public impeachment hearing of President Donald Trump's efforts to tie U.S. aid for Ukraine to investigations of his political opponents. (AP PhotoJulio Cortez)

Lt. Col. Alexander Vindman arrives to testify before the House Intelligence Committee on Capitol Hill in Washington, Tuesday, Nov. 19, 2019, during a public impeachment hearing of President Donald Trump's efforts to tie U.S. aid for Ukraine to investigations of his political opponents. (AP PhotoJulio Cortez)

In all, nine witnesses are testifying in a pivotal week as the House’s historic impeachment inquiry accelerates and deepens.