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Acting US Ambassador to Ukraine Bill Taylor testified today that he was told by Ambassador to the European Union Gordon Sondland that security aid to Ukraine could have been held up in part because of a push for Ukraine to publicly announce an investigation that could help the President politically, according to sources in both parties.

In a lengthy and detailed opening statement, Taylor said that he and Sondland spoke by phone about why the aid was frozen, and Sondland cited the need for Ukraine to open an investigation among other reasons, according to the sources.

Sondland told Taylor that the investigations potentially included both Ukraine’s involvement in the 2016 election and Burisma, the Ukrainian energy company that hired former Vice President Joe Biden’s son Hunter Biden, the sources said.

Asked about Taylor’s comments, a source familiar with Sondland’s testimony said that Sondland cited, in addition to the investigations, that the aid may have been frozen because the Europeans weren’t giving Ukraine enough and corruption generally. He said Sondland was only speculating when he referenced the political investigations into the 2016 election and Burisma.

“He made very clear in his testimony that nobody would give him a straight answer” about why the aid was being held up, the source of Sondland’s testimony.

Some background: Text messages between Taylor and Sondland and provided to Congress showed that the two discussed the aid being frozen on the phone, amid concerns Taylor had raised that it was being held up in order to help the President politically.

“As I said on the phone, I think it’s crazy to withhold security assistance for help with a political campaign,” Taylor texted Sondland on Sept. 9. Sondland then discussed the concern with the President and then texted Taylor there was no quid pro quo.