The source of this is Congressman Peter Roskam, but you can listen to the nine second snippet of what Democratic Party opponent Sean Casten says on YouTube:

VIDEO: Roskam’s Opponent Sean Casten Falsely Claims There Were White Supremacist Gestures During Kavanaugh’s Hearing

During the Daily Herald editorial board debate Monday, Peter Roskam’s opponent surprised everyone in the room by echoing a debunked conspiracy theory by falsely claiming Zina Bash displayed white supremacist gestures during Supreme Court nominee Brett Kavanaugh’s hearing.

The Washington Post and other news outlets have addressed this conspiracy theory and said there was no credible evidence to suggest this occurred.

“Sean Casten is unfit to serve in Congress as he falsely claimed an aide to Judge Kavanaugh is a white supremacist after previously claiming those who work in the White House are Nazis,” said Roskam for Congress Spokesman Veronica Vera.

“Conspiracy theories and hateful, false rhetoric are tearing our country apart and Peter Roskam has proven he can reach across the aisle, work with others and get things done in Washington.”