a key witness-- how a key witness changed his testimony. gordon sondland, a top u.s. diplomat, now says he believes the trump administration demanded a quid pro quo from ukraine. nancy cordes is at the capital, and nancy, did we learn why sondland changed his story? >> reporter: well, in a way, norah, sondland had the change his original testimony because so many of the other witnesses had disputed it. so in this new three-page addendum, she says that reading those other witness statements, "refreshed his recollection about his role in the president's quid pro quo." >> it's never too late to do the right thing. >> reporter: that was the democrat's reaction to an about- face from ambassador gordon sondland, who says he does now recall telling a ukrainian official in early september that resumption of u.s. aid would likely not occur until ukraine provided a public anti- corruption statement, specifically announcing an