(CNN) Senate Judiciary Chairman Chuck Grassley on Thursday referred Julie Swetnick and her lawyer Michael Avenatti to the Department of Justice for a possible criminal investigation over allegations they made false statements to Congress about now-Supreme Court Justice Brett Kavanaugh.

"I am writing to refer Mr. Michael Avenatti and Ms. Julie Swetnick for investigation," Grassley wrote in a letter to Attorney General Jeff Sessions and FBI Director Christopher A. Wray, for potential "materially false statements they made to the Committee during the course of the Committee's investigation. "

In a statement, Grassley said, "When a well-meaning citizen comes forward with information relevant to the committee's work, I take it seriously. It takes courage to come forward, especially with allegations of sexual misconduct or personal trauma. I'm grateful for those who find that courage."

Grassley continued, "But in the heat of partisan moments, some do try to knowingly mislead the committee. That's unfair to my colleagues, the nominees and others providing information who are seeking the truth."

Avenatti, a potential 2020 Democratic presidential candidate, told CNN that the referral is "completely baseless and political."

Read More