President Trump attacked former Ukraine Ambassador Marie Yovanovitch in a pair of tweets as she testified Friday in the House's impeachment inquiry.

Everywhere Marie Yovanovitch went turned bad. She started off in Somalia, how did that go? Then fast forward to Ukraine, where the new Ukrainian President spoke unfavorably about her in my second phone call with him. It is a U.S. President’s absolute right to appoint ambassadors.

They call it “serving at the pleasure of the President.” The U.S. now has a very strong and powerful foreign policy, much different than proceeding administrations. It is called, quite simply, America First! With all of that, however, I have done FAR more for Ukraine than O.

The big picture: White House Press Secretary Stephanie Grisham told reporters earlier today that Trump "will be watching [ranking House Intelligence Committee member Rep. Devin Nunes'] opening statement, but the rest of the day he will be working hard for the American people."

Trump's 10:01 a.m. tweet came 35 minutes after Nunes' opening statement concluded at 9:26 a.m.

House Intelligence Chairman Adam Schiff (D-Calif.) read the tweets directly to Yovanovitch about 20 minutes after Trump posted them, adding that "some of us here take witness intimidation very seriously."

"It's very intimidating. ... I mean, I can't speak to what the president is trying to do, but I think the effect is trying to be intimidating."

The state of play: Multiple House Democrats have said during a break in the hearing that Trump's tweets may trigger an article of impeachment, Axios' Alayna Treene reports.

She adds that Trump's tweet is the type of attack that Republicans told her they were hoping to avoid today.

Grisham issued a statement on Trump's tweet, saying, "The tweet was not witness intimidation, it was simply the president’s opinion, which he is entitled to. This is not a trial, it is a partisan political process — or to put it more accurately, a totally illegitimate, charade stacked against the president. There is less due process in this hearing than any such event in the history of our country. It’s a true disgrace."

Watch video of Yovanovitch's exchange with Schiff:

Go deeper: Live updates on Yovanovitch's impeachment hearing