WASHINGTON — Ambassador Gordon Sondland declared to impeachment investigators Wednesday that President Donald Trump and his lawyer Rudy Giuliani explicitly sought a “quid pro quo” with Ukraine, leveraging an Oval Office visit for political investigations of Democrats. But he also came to believe the trade involved much more.

Besides the U.S. offer of a coveted meeting at the White House, Sondland testified it was his understanding the president was holding up nearly $400 million in military aid, which Ukraine needed with an aggressive Russia on its border, in exchange for the country’s announcement of the investigations.

Sondland conceded that Trump never told him directly the security assistance was blocked for the probes, a gap in his account that Republicans and the White House seized on as evidence the president did nothing wrong. But the ambassador said his dealings with Giuliani, as well as administration officials, left him with the clear understanding of what was at stake.

“Was there a ‘quid pro quo?'” Sondland testified in opening remarks. “With regard to the requested White House call and White House meeting, the answer is yes.”

The rest, he said, was obvious: “Two plus two equals four.”

Later Wednesday, another witness undercut a main Republican argument — that Ukraine didn’t even realize the money was being held up. The Defense Department’s Laura Cooper testified that Ukrainian officials started asking about it on July 25, which was the day of Trump’s phone call with the country’s new president when he first asked for a “favor.”

Sondland, the ambassador to the European Union and a major donor to Trump’s inauguration, was the most highly anticipated witness in the House’s impeachment inquiry into the 45th president of the United States.

In his testimony, he painted a picture of a Ukraine pressure campaign that was prompted by Trump himself, orchestrated by Giuliani and well-known to other senior officials, including Secretary of State Mike Pompeo. Sondland said he raised his concerns about a quid pro quo for military aid with Vice President Mike Pence — a conversation a Pence adviser vigorously denied.

Pompeo also dismissed Sondland’s account.

However, Sondland said, “Everyone was in the loop. It was no secret.”

The ambassador said that he and Trump spoke directly about desired investigations, including a colorful cellphone call this summer overheard by others at a restaurant in Kyiv.

Trump himself insists daily that he did nothing wrong and the Democrats are just trying to drum him out of office.

As the hearing proceeded, he spoke to reporters outside the White House. Reading from notes, Trump quoted Sondland quoting Trump to say the president wanted nothing from the Ukrainians and did not seek a quid pro quo.

The impeachment inquiry focuses significantly on allegations that Trump sought investigations of former Vice President Joe Biden and his son — and the idea that Ukraine rather than Russia interfered in the 2016 U.S. election — in return for the badly needed military aid for Ukraine and the White House visit.

Another hearing in the impeachment inquiry gaveled open Wednesday evening with Cooper, a Defense Department official who had raised concerns about the suspended Ukraine aid, and David Hale, the No. 3 official at the State Department.

Sondland said that conditions on any potential Ukraine meeting at the White House started as “generic” but more items were “added to the menu including — Burisma and 2016 election meddling.” Burisma is the Ukrainian gas company where Biden’s son Hunter served on the board. And, he added, “the server,” the hacked Democratic computer system.