Washington (CNN) President Donald Trump on Sunday lashed out at Jennifer Williams , a State Department employee who is set to testify publicly this week, the latest in a series of social media attacks by the President on those cooperating with the House impeachment inquiry.

Williams, an aide to Vice President Mike Pence and a career foreign service officer, is scheduled to appear before the House Intelligence Committee on Tuesday. In his tweet, Trump resurfaced an unfounded accusation he has raised against other officials who have testified in the probe, characterizing Williams as a Never Trumper and associating her with other "Never Trumpers."

"Jennifer is a State Department employee," Pence's press secretary Katie Waldman said in response to CNN's request for comment.

Trump's attacks on Williams come after he tweeted Friday as former Ambassador Marie Yovanovitch's was testifying that "everywhere Marie Yovanovitch went turned bad" -- an attack Democrats may treat as witness intimidation.

It's the most predictable pattern in Washington: Trump will attack when cornered. He clearly feels cornered by anyone and everything associated with the impeachment inquiry. That includes a frustrated and unwilling witness like Williams. It doesn't matter if you're an active-duty military person, an ambassador, a current or former member of his staff, or Pence's. What ties these people is not that they oppose Trump. They don't. They all work or worked for him. What ties them is that they have sworn an oath to tell the truth under threat of perjury about what happened here.

The Latest

Saturday testimony behind closed doors -- Mark Sandy, a senior career official at the Office of Management and Budget, testified Saturday about a budget process that went off the rails Mark Sandy, a senior career official at the Office of Management and Budget, testified Saturday about a budget process that went off the rails when nearly $400 million in US military aid to Ukraine was withheld earlier this year, and that he did not know for sure the reasoning behind the freeze in funds, sources familiar with his testimony told CNN.

Republican congressman calls new details 'alarming' -- Rep. Mike Turner, a Republican member of one of the Rep. Mike Turner, a Republican member of one of the House committees involved in the impeachment inquiry told CNN's Jake Tapper on "State of the Union" Sunday that information provided about the President during closed-door depositions "is alarming" and "not okay."

"As I've said from the beginning, I think this is not okay. The President of the United States shouldn't even in the original phone call be on the phone with the president of another country and raise his political opponent," Turner said.

Republican congressman has no issue with State Department releasing documents, on one major condition -- Rep. Chris Stewart told ABC's George Stephanopoulos on "This Week" that he has no issue with the State Department releasing documents and having a White House official testify, as requested by the House Intelligence Committee's impeachment inquiry -- though he tied the release to Rep. Chris Stewart told ABC's George Stephanopoulos on "This Week" that he has no issue with the State Department releasing documents and having a White House official testify, as requested by the House Intelligence Committee's impeachment inquiry -- though he tied the release to an agreement for the whistleblower to testify , which Democrats have indicated is a nonstarter.

Fresh testimony released

Gordon Sondland , the American envoy to the European Union, was acting at Trump's instruction in his dealings with Ukraine, and Sondland said that the President told Ukrainian President Volodymyr Zelensky he "must announce the opening of the investigations," according to transcript of the closed-door deposition of former National Security Council official, Tim Morrison, that was released Saturday.

Morrison testified that he had heard from Sondland that US aid to Ukraine was conditioned on the country announcing an investigation into former Vice President Joe Biden and his son Hunter Biden. There has been no evidence of wrongdoing by either Biden.

CNN Exclusive: Giuliani associate said he was on 'secret mission' for Trump

Eventually, according to what Parnas told his confidants, the topic turned to Ukraine. According to those two confidants, Parnas said that "the big guy," as he sometimes referred to the President in conversation, talked about tasking him and Fruman with what Parnas described as "a secret mission" to pressure the Ukrainian government to investigate Joe Biden and his son Hunter.

As a reminder -- Prosecutors allege Parnas and Fruman illegally funded Republican politicians and campaigns with money from foreign nationals in attempts to buy influence. That pair are also said to have aided Giuliani, Trump's personal lawyer, in an effort to investigate Biden.

Trump has publicly said he didn't know the pair. CNN's KFile reported earlier this month on a series of photos that show 10 interactions between Trump and Parnas and Fruman, including VIP photos at campaign events, attendance at high-dollar fundraisers and a retreat.

45 ways Trump has been dishonest about Ukraine

Back to back to back hearings this week

The House Intelligence Committee will hear publicly from eight witnesses over three days this week as Democrats push to complete their impeachment proceedings against Trump before the end of the year.

Here's the lineup:

November 19

Williams, an aide to Pence.

Lt. Col. Alexander Vindman, the National Security Council's top Ukraine expert.

Kurt Volker, the former US special envoy to Ukraine.

Morrison, the top Russia and Europe adviser on the National Security Council.

November 20

Sondland, the American envoy to the European Union

Laura Cooper, a deputy assistant secretary of defense for Russia, Ukraine and Eurasia.

David Hale, the under secretary of state for political affairs.

November 21