Washington (CNN) House Intelligence Chairman Adam Schiff made clear on Saturday that the Ukraine whistleblower won't be testifying in the impeachment inquiry, arguing that the individual's testimony would be "redundant and unnecessary."

House Republicans earlier Saturday had submitted a list of witnesses to Democrats that they'd like to testify as part of the chamber's impeachment inquiry into President Donald Trump and Ukraine. The list included the whistleblower and former Vice President Joe Biden's son Hunter Biden.

In a letter obtained by CNN, Schiff goes further than he did earlier in the day when he said in a statement that his committee would evaluate the witness requests and "give due consideration to witnesses within the scope of the impeachment inquiry, as voted on by the House."

"The impeachment inquiry, moreover, has gathered an ever-growing body of evidence -- from witnesses and documents, including the President's own words in his July 25 call record -- that not only confirms, but far exceeds, the initial information in the whistleblower's complaint. The whistleblower's testimony is therefore redundant and unnecessary. In light of the President's threats, the individual's appearance before us would only place their personal safety at grave risk," Schiff wrote to California Rep. Devin Nunes, the top Republican on the House Intelligence Committee.

The comments by Schiff, one of the Democrats in charge of the inquiry, are the clearest yet that the whistleblower won't testify in the probe, a dramatic shift since the beginning of the impeachment inquiry in September when the individual's testimony was viewed as paramount. The committee had engaged in a round of private talks to protect the whistleblower while allowing him or her to provide testimony, including disguising the individual's identity or conducting the interview off-site.

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