His note came less than two hours before POLITICO broke the story about the aid freeze and upended delicate negotiations led by Trump's handpicked backchannel to Ukraine to try to get an investigation announced into Joe Biden.

At the time, President Donald Trump’s personal attorney was deeply enmeshed in the roots of the Ukraine saga — calling and arranging meetings with top Ukrainian officials to press them to investigate the former vice president and his son Hunter.

But despite reams of testimony from high-level officials in the White House, State Department and Pentagon, House impeachment investigators have yet to establish whether Giuliani knew that Trump had ordered the military aid to Ukraine be withheld.

The question matters, particularly because Democrats are eager to tie Trump closer into the Ukraine scheme, which they view as a simple tale of extortion. The movements of Giuliani are central to their case.

And if Giuliani did know the aid was frozen, it would have provided him with a crucial point of leverage over the country's new president, Volodymyr Zelensky as Giuliani sought to secure investigations favored by Trump.

Many senior State Department and White House officials inside the Trump administration were aware of the hold on military assistance well before the POLITICO report. That includes two officials who had routine conversations with Giuliani, according to their testimony and text messages released to lawmakers.

U.S. Ambassador to the European Union Gordon Sondland and former Ambassador Kurt Volker learned of the aid freeze on July 18, the same day White House budget officials announced it on an interagency video call. The top U.S. envoy to Ukraine, William Taylor, texted Sondland and Volker about the unexpected hold later that day.

"[Budget officials] just now said that all security assistance to Ukraine is frozen, per a conversation with [White House chief of staff Mick] Mulvaney and POTUS," Taylor said in a text. "Over to you."

Sondland replied, "All over it."

Volker, who had been in touch with Giuliani for weeks, was texting the former New York City mayor the next day.

"Mr. Mayor -- really enjoyed breakfast this morning," Volker texted Giuliani on July 19, in a message that CCed one of Zelesnky's top aides. "As discussed, connecting you here with Andrey Yermak, who is very close to President Zelensky. I suggested we schedule a call together on Monday."

Less than two weeks later, Volker and Giuliani were texting about Giuliani's planned trip to Madrid to meet Yermak in person, and Volker copied Sondland on the chain.

"Seeing Yermak in Madrid tomorrow," Giuliani wrote. "Would like to meet with Gordon also."

"Rudy great ... I will be in DC on the 12. Will you be there or in NY?" Sondland asked.

Despite many hours of testimony in which they expressed urgent concerns about the hold on military assistance, neither Sondland nor Volker have indicated whether they — or Trump, Mulvaney or anyone else in the president's inner circle — ever informed Giuliani about it even as they facilitated his meetings with senior Ukrainian officials.

Giuliani has declined further attempts to clarify the matter and has not responded to six requests for comment this month.

Volker and Sondland also declined to comment. But both men described how they reacted with alarm after learning that Trump ordered a hold on the $400 million package of aid sometime in July, even though the State Department, Pentagon and National Security Council had unanimously agreed it should be issued immediately to support Ukraine as it fends off a Russian military incursion in its Donbas region.