Cooper took to Twitter to criticize Sanders writing, "Sarah Huckabee Sanders even looked habitually pissed when she was a teenager! I guess having @GovMikeHuckabee as your dad does that to you."
However, the photo he posted, which he believed was a teenage snapshot of the press secretary, was actually a still-frame of Philipps' character Kim Kelly from the beloved 1999 NBC dramedy Freaks and Geeks.
Philipps was quickly alerted to the mix-up, which riled up her fans, and the 38-year-old actress responded to Cooper's post with a series of tweets chastising the veteran politician both for getting them confused and for mocking Sanders' appearance.
"ARE YOU F**KING KIDDING ME? IS THIS A JOKE? THIS IS ME FROM FREAKS AND GEEKS. FAKE NEWS," she began a series of tweets. "ALSO I LOOK NOTHING LIKE SARAH HUCKABEE SANDERS. WHAT IN THE ACTUAL -?!?????!!!!! I AM NEVER GETTING OVER THIS. I AM ACTUALLY DEAD NOW."
When one Twitter user wrote to Philipps that Cooper was a fan of hers, she replied, "APPARENTLY NOT SINCE HE THINKS IM SARAH HUCKABEE SANDERS."
Philipps concluded, "Pick on a woman for the insane lies she tells. Not cause she looks pissed off while telling them. I love women who look pissed off."
Cooper was soon alerted to his mistake by her many fans and he went on to delete the tweet, before posting an apology.
"I deleted this tweet after I found out the pic wasn’t Sanders but rather an actress w/ a huge fan base (who now all HATE me, lol)," Cooper tweeted, along with a screen shot of the tweet he had just deleted. "My bad!"
Cooper added, "My advice: Just because a Google search identifies an image as being a certain person, take that with a grain of salt! It could be wrong."
Cooper went on to argue with other twitter users in the replies to his apology. When asked if he's ever seen Freaks and Geeks, Cooper wrote, "I'm sure my kids watched it, but I don't think I ever saw the show. Based on the feedback from fans, however, it must have been great!!"