Lawmakers plan to grill Ambassador to the European Union Gordon Sondland on Thursday about a private discussion he had with top Ukrainian officials in the White House in which he explicitly mentioned the Ukrainian gas company linked to Hunter Biden, amid negotiations over granting Ukraine’s new president an audience with President Donald Trump, NBC News has learned.

Sondland’s meeting with the Ukrainians just steps away from the White House Situation Room came minutes after a larger West Wing meeting that included then-National Security Adviser John Bolton, who had been noncommittal about scheduling a meeting between Trump and new Ukrainian President Volodymyr Zelenskiy. Sondland directly contradicted Bolton by telling the Ukrainians that in fact, Trump was committed to meeting with Zelenskiy on the condition he open a corruption investigation, two people told about the matter tell NBC News.

Bolton abruptly ended the meeting.