Sondland, whose name surfaced in a whistleblower complaint in August, is certain to be asked about text messages that show him working with two other diplomats to navigate the interests of Trump and his Giuliani. The messages show the diplomats discussing an arrangement in which Ukraine’s leader would be offered a White House visit in exchange for a public statement by Ukraine committing to undertake investigations into Trump-backed conspiracy theories about interference in the 2016 presidential election and Burisma.