WASHINGTON, DC - NOVEMBER 13: U.S. President Donald Trump walks along the colonnade after greeting Turkish President Recep Tayyip Erdogan upon his arrival at the South Portico of the White House on November 13, 2019 in Washington, DC.

The call was first revealed on Wednesday by Trump's top diplomat in Ukraine, William Taylor, who testified about it before the House Intelligence Committee. The committee is holding impeachment hearings into the president's decision to freeze foreign aid to Ukraine while his administration pressured the country to launch investigations that would benefit Trump politically.

President Donald Trump on Wednesday said he could not recall a phone call he allegedly had with his ambassador to the European Union, Gordon Sondland, on July 26, one day after Trump had asked Ukrainian President Volodymyr Zelenskiy for "a favor."

"I know nothing about that, first time I've heard," Trump said of the newly revealed call. "The one thing I know about Sondland is that he did speak to me for a brief moment, and I said 'no quid pro quo,'" Trump told reporters during a press conference with Turkish President Recep Erdogan.

"I've never heard this," Trump continued. "In any event, it's more secondhand information, but I've never heard it."

Asked by a reporter whether he recalled the conversation, Trump responded, "No, I don't recall, not even a little bit. The only thing, and I guess Sondland stated with his testimony, is there was no quid pro quo."

Taylor testified Wednesday that during the alleged call, an aide to Taylor, David Holmes, heard the president ask Sondland about "the investigations."

According to Taylor, Holmes was sitting with Sondland at a restaurant in Kyiv on July 26 and heard Sondland tell the president "that the Ukrainians were ready to move forward" with the two investigations.

Taylor added: "Following the call with President Trump, [Holmes] asked Ambassador Sondland what President Trump thought about Ukraine. Ambassador Sondland responded that President Trump cares more about the investigations of Biden" than about Ukraine itself.

Holmes is scheduled to testify behind closed doors to House investigators in the coming days. Sondland has already given a deposition, in which he said Trump told him in a later phone call that there were no conditions being placed on military aid to Ukraine.