The State Department on Tuesday directed Gordon Sondland, the U.S. ambassador to the European Union, not to testify before House investigators heading up the Democrats’ impeachment probe against President Donald Trump.

Sondland was scheduled to appear privately before the House intelligence, foreign affairs, and oversight committees. The chairmen of each panel are looking to determine whether President Trump wanted to withhold military aid to Ukraine to pressure President Volodymyr Zelensky into investigating former Vice President and Democrat rival Joe Biden and his son, Hunter Biden.

Sondland’s attorney said the ambassador was ordered by the State Department not to appear, while the New York Times reported earlier the appearance was blocked by the White House.

“Ambassador Sondland had previously agreed to appear voluntarily today, without the need for a subpoena, in order to answer the committee’s questions on an expedited basis,” Sondland’s attorney, Jim McDermott, said in a statement. “As the sitting U.S. Ambassador to the EU and employee of the State Department, Ambassador Sondland is required to follow the department’s direction.”

Text messages revealed by ABC News show Sondland defended President Trump’s July 25th telephone call with the leader of Ukraine, affirming the president had said, “no quid pro quo of any kind” occurred between the two.

The texts show Bill Taylor, the top U.S. diplomat to Ukraine, wrote to Sondland, “I think it’s crazy to withhold security assistance for help with a political campaign,” seemingly a reference to allegations made by a partisan CIA officer’s complaint regarding the Trump-Zelensky call.

“The president has been crystal clear no quid pro quo of any kind,” Sondland replied. “The president is trying to evaluate whether Ukraine is truly going to adopt the transparency and reforms that President Zelensky promised during his campaign. I suggest we stop the back and forth by text.”

The texts were provided by Kurt Volker, former U.S. special envoy to Ukraine, during a closed-door testimony before House lawmakers last week.

The Trump-Zelensky conversation prompted House Democrats to launch a so-called formal impeachment inquiry into the president — despite the fact that the world leaders have both denied any pressure was applied to investigate the Bidens. In a nod to transparency, the White House released a transcript of the call to show no wrongdoing occurred.

In a pair of tweets, President Trump defended the move to block Sondland’s testimony, stating the U.S. diplomat would have been appearing before a “kangaroo court.”

“I would love to send Ambassador Sondland, a really good man and great American, to testify, but unfortunately he would be testifying before a totally compromised kangaroo court, where Republican’s rights have been taken away, and true facts are not allowed out for the public to see,” the president tweeted. “Importantly, Ambassador Sondland’s tweet, which few report, stated, “I believe you are incorrect about President Trump’s intentions. The President has been crystal clear: no quid pro quo’s of any kind.” That says it ALL!”

….to see. Importantly, Ambassador Sondland’s tweet, which few report, stated, “I believe you are incorrect about President Trump’s intentions. The President has been crystal clear: no quid pro quo’s of any kind.” That says it ALL! — Donald J. Trump (@realDonaldTrump) October 8, 2019

The UPI contributed to this report.