Senate Judiciary Committee Chairman Chuck Grassley, R-Iowa, has requested Fusion GPS, the opposition research firm that hired a former British intelligence officer who wrote the so-called “Trump dossier,” provide information about how its founder mischaracterized certain statements from his testimony before the panel about an insider within the Trump Organization.

Grassley submitted a letter on Thursday to Fusion GPS lawyer Joshua Levy concerning Fusion GPS founder Glenn Simpson’s testimony, where Simpson claimed the dossier author, Christopher Steele, was told that the FBI had a voluntary walk-in source from inside the Trump Organization or campaign that confirmed aspects of the dossier.

Top Democrat of the Judiciary Committee Sen. Dianne Feinstein, D-Calif., released a transcript of Simpson’s testimony earlier this week after Grassley refused to heed calls by Simpson and Democrats to release the record of the August 2017 interview.

Grassley noted that while some news outlets initially reported "a voluntary walk-in source from inside the Trump Organization or campaign" "as fact," subsequent reporting cited “a source close to Fusion GPS” claiming that Simpson mischaracterized the source and that he was actually referring to the Australian diplomat that reportedly provided information to the FBI about a conversation he exchanged with Trump campaign adviser, George Papadapolous.

Papadopoulos, who pled guilty in October to lying to the FBI, told the diplomat he had been informed the Russian government had hacked Clinton campaign emails, according to a New York Times report in late December 2017. It is unknown whether Papadopoulos tried to obtain the emails himself or if he informed the Trump campaign about them.

Grassley asked in his letter whether the original statement to the committee was accurate. If not, Grassley wants to know how Levy and Fusion realized there was a mistake in the transcript and whether that occurred before or after they reviewed the transcript for roughly 14 hours.

“Given that sources close to your client are reportedly trying to correct the public record regarding his statements to the Committee about this purported source, the questions arises as to whether or when your client plans to correct the Committee’s record,” Grassley wrote.

“Neither you nor he has attempted to correct this alleged mischaracterization in his statements,” the Republican added.

The letter requests that Levy and Fusion respond by Jan. 18.