Common Cause said in a statement Thursday it condemns "bigotry and hate speech in every form."
The comments were made during interviews by conservative activist and videographer Christian Hartsock, who has contributed to Andrew Breitbart's BigGovernment.com.
Hartsock's footage created a buzz in the blogosphere after being posted on YouTube. In it, Hartsock is heard laughing as he goads his subjects with questions like, "After we impeach Clarence Thomas, what do we do with him?"
One woman suggests the Supreme Court justice should be lynched, while a man says, "Put him back in the fields."
Police arrested 25 people for trespassing Sunday, the second day of a four-day conclave of wealthy conservative political activists organized by brothers David and Charles Koch of Kansas-based Koch Industries.