As an impeachment inquiry deepens, Congress has received a text-message exchange featuring U.S. Ambassador Gordon Sondland discussing President Donald Trump's dealings with Ukraine, ABC News reports.

The group texts include federal diplomat Bill Taylor expressing concern about Trump's request that the Ukrainians investigate Joe Biden's son: "I think it's crazy to withhold security assistance for help with a political campaign."

Sondland, the U.S. ambassador to the European Union, replies by defending the president. "Bill, I believe you are incorrect about President Trump's intentions," Sondland texts. "The President has been crystal clear: no quid pro quo's of any kind. The President is trying to evaluate whether Ukraine is truly going to adopt the transparency and reforms that President Zelensky promised during his campaign."

ABC says Sondland then suggests that the diplomats stop having this conversation in writing. "I suggest we stop the back and forth by text," he writes.

The text messages appear to have been exchanged this summer but were sent to Congress this week by former U.S Special Envoy to Ukraine Kurt Volker as he's deposed by the U.S. House of Representatives. They are the latest documents in the impeachment inquiry to feature Sondland, the founder and former CEO of Provenance Hotels, which owns or operates six hotels in downtown Portland, including the Heathman and the Sentinel.

A spokesman for Sondland directed ABC News' questions to the White House. Through a spokesman, Sondland has previously declined comment to WW regarding the Ukraine matter.

UPDATE, 10:45 pm: The New York Times alleges that Sondland "worked on a statement for the country's new president in August that would have committed Ukraine to pursuing investigations sought by Mr. Trump into his political rivals."

And House Democrats have released fuller transcripts of Sondland's group texts.