Democrat Ted Lieu has accused of Republican Devin Nunes of conspiring with Lev Parnas.
Parnas is one of the center pieces of the Ukraine scandal and associate of President Trump's personal lawyer, Rudy Giuliani.
A lawyer for Nunes sent a letter to Lieu threatening legal action if he did not apologize for his comments.
Lieu responded on Friday with his own letter, daring Nunes to file a lawsuit.
He capped it by saying "take your letter and shove it."