Donald Trump Jr. has hit out at "Jeopardy!" star Ken Jennings for mocking Trump Jr.'s younger brother, Barron, accusing him of "bullying a kid."
The feud stems from comedienne Kathy Griffin's widely-condemned photo shoot in which she held up a fake severed head that was meant to resemble President Donald Trump.
After TMZ reported that 11-year-old Barron was unsure at first whether the photos were real, Jennings ridiculed Barron on Twitter.
"Barron Trump saw a very long necktie on a heap of expired deli meat in a dumpster," Jennings wrote, according to the Daily Mail. "He thought it was his dad & his little heart is breaking."
Trump Jr. immediately took exception to Jennings' tweet.
"It takes a real man to pick on an 11 year old," he wrote. "Yet another low from the left, but they will rationalize this away with their usual excuses."
The "Jeopardy!" champion, whose 74-game winning streak in 2004 is the longest in the program's history, refused to walk back his comments, instead taking a shot at Trump Jr. himself.
"I will kill as many white rhinos as it takes to prove my masculinity to Donald Trump Jr," Jennings wrote, in an apparent reference to Trump Jr.'s controversial hunting activity.
Following his "Jeopardy!" success, Jennings went on to become an author of educational books for children. His book series is called "Junior Genius Guides" and is published by Simon & Schuster.
In the wake of Jennings' tweets, a number of people have begun lobbying Simon & Schuster to discontinue its relationship with him.
"He writes children's books for Simon & Schuster," a twitter user told Trump Jr. "Call them ... then [choose] option 4. Yes, this is the jacka -- from Jeopardy."
To which Trump Jr. responded: "Good point, you would think that in this day & age [Simon & Schuster] would have an issue with one of their children's authors bullying a kid."
Griffin has faced enormous backlash over the photo shoot, receiving criticism from people across the political spectrum, from President Donald Trump himself to Chelsea Clinton to her CNN colleague, Anderson Cooper.
"Kathy Griffin should be ashamed of herself," the president wrote on Twitter. "My children, especially my 11-year-old son, Barron, are having a hard time with this. Sick!"
Griffin has since issued a public apology, conceding that the photos were "too disturbing."
"I beg for your forgiveness. I went too far," she said in an Instagram video, according to CNN. "I made a mistake and I was wrong."
Shortly after the images were published, CNN confirmed that it was terminating its contract with Griffin, who has co-hosted the network's New Year's Eve special with Anderson Cooper since 2007.