WASHINGTON — A second U.S. Embassy staffer in Kyiv overheard a cell phone call between President Donald Trump and his ambassador to the European Union discussing a need for Ukrainian officials to pursue “investigations,” The Associated Press has learned.

The July 26 call between Trump and Gordon Sondland was first described during testimony Wednesday by William Taylor, the acting U.S. ambassador to Ukraine. Taylor said one of his staffers overhead the call while Sondland was in a Kyiv restaurant the day after Trump's July 25 phone call with Ukrainian President Volodymyr Zelenskiy that triggered the House impeachment inquiry.

The second diplomatic staffer also at the table was Suriya Jayanti, a foreign service officer based in Kyiv. A person briefed on what Jayanti overheard spoke to AP on condition of anonymity to discuss a sensitive matter currently under investigation.

The accounts of the two embassy staffers could tie Trump closer to alleged efforts to hold up military aid to Ukraine in exchange for investigations into political rival Joe Biden and his son Hunter's business dealings. In defending Trump on Wednesday, Republicans repeatedly highlighted that Taylor never directly heard the president direct anyone to demand that the Ukrainians open the probe.

Trump on Wednesday said he did not recall the July 26 call with Sondland.

“No, not at all, not even a little bit,” Trump said.

The White House did not respond to questions Thursday about the second witness to the call with Sondland.

The staffer Taylor testified about is David Holmes, the political counselor at the embassy in Kyiv, according to an official familiar with the matter who spoke on condition of anonymity.

Holmes is scheduled to testify Friday before House investigators in a closed session.

Taylor was one of the first witnesses called Wednesday during the impeachment inquiry's initial open hearing. He testified that his staffer could hear Trump on the phone asking Sondland about “the investigations.”

Later that day, a Twitter account that appears to belong to Ukraine's then-Defense Minister Oleksandr Danylyuk posted a photo of himself at dinner with Sondland, Taylor and Ambassador Kurt Volker, who was then Trump's special envoy to Ukraine for peace negotiations.

Since 2014, the Ukrainian government has been battling Russian-backed separatists in the country's eastern region, and the continuation of U.S. military aid is crucial to its defense. Whether Trump directed nearly $400 million in aid to be withheld to force the Ukrainians to open investigations into Democrats is a key question of the impeachment inquiry.

Current and former U.S. officials say Sondland's use of a cell phone in a public place in Ukraine to speak with anyone in the U.S. government back home about sensitive matters, let alone the president, would be a significant breach of communications security.