The ranking Republican on the Judiciary Committee and Trump ally, Doug Collins (R-Georgia), has called for House Intelligence Committee Chairman Adam Schiff (D-California) to testify in his committee’s impeachment hearing.

A panel of expert witnesses will testify before the House Judiciary Committee on Wednesday, as they consider articles of impeachment against President Donald Trump.

“First and foremost, the first person that needs to testify is Adam Schiff. Adam Schiff is the author of this report,” Collins said during an interview on Fox News Sunday. He added, if Schiff “chooses not to testify, then I really question his veracity and what he’s putting in his report.”

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Collins also claimed that Schiff has withheld documents.

“If they think they have such a case, give us all the materials,” he said.

Schiff told CNN last week that he would not testify in a Senate impeachment trial should the House vote on articles of impeachment. He said that Republicans demanding his testimony indicate that “they are not serious about what they are doing.”

“There is nothing to testify about. I think if the President or his allies in the Senate persist it means they are not serious about what they are doing,” Schiff said. “What would I offer in terms of testimony that I heard Dr. (Fiona) Hill in open hearing say such and such? That is not pertinent. The only reason for them to go through with this is to mollify the President and that is not a good reason to try to call a member of Congress as a witness.”