President Trump blasted former U.S. Ambassador to Ukraine Marie Yovanovitch during her public testimony before the House Intelligence Committee on Friday, saying everywhere she went as a diplomat "turned bad."

House Intelligence Chairman Adam Schiff, D-Calif., read the tweet to Yovanovitch during the hearing and accused the president of "witness intimidation."

But Stephanie Grisham, the White House press secretary, pushed back in a statement Friday: "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."

Yovanovitch appeared before the committee on the second day of the Democrats' impeachment inquiry.

The president first hit Yovanovitch for her time serving in Somalia. "How did that go?" he wrote.

Yovanovitch is a career foreign service officer with more than 30 years at the State Department, having also served in Somalia, Armenia, Kyrgyzstan and Russia.

The president continued: "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,'" he said, in a second tweet.

"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," he wrote.

In an exchange a few minutes later with Schiff, D-Calif., Yovanovitch responded to the president's tweets.

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"I don’t think I have such powers — not in Mogadishu, Somalia and other places. I actually think that where I've served over the years, I and others have demonstrably made things better, you know, for the U.S. as well as the countries that I’ve served in," she said. "Ukraine, for example, where there are huge challenges — including on the issue that we're discussing today of corruption. Huge challenges."

"But they’ve made a lot of progress since 2014, including in the years that I was there. And I think, in part, Ukrainian people get the most credit for that, but a part of that credit goes to the work of the United States and to me as the ambassador in Ukraine."

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

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Yovanovitch's appearance follows the testimony earlier this week from U.S. chargé d'affaires in Ukraine Bill Taylor and Deputy Assistant Secretary of State for Europe George Kent.

“The former ambassador from the United States, the woman, was bad news,” was how Trump described Yovanovitch to Ukrainian President Volodymyr Zelensky in a July 25 phone call.

“She’s going to go through some things,” the president added ominously.

Fox News' Tyler Olson and Gregg Re contributed to this report.