All week Mitt Romney has quoted one of his favorite TV series to punctuate the poignant stories of lives cut short that he has woven into his campaign speeches.
But on Friday the creator of the series, “Friday Night Lights,†accused Mr. Romney of plagiarism for adopting the slogan, “Clear Eyes, Full Hearts, Can't Lose,'' and asked him to stop using it.
“Your politics and campaign are clearly not aligned with the themes we portrayed in our series,†Peter Berg, the writer-director of the show, wrote in a letter to Mr. Romney.
“The only relevant comparison I see between your campaign and ‘Friday Night Lights' is in the character of Buddy Garrity â€" who turned his back on American ca r manufacturers, selling imported cars from Japan.â€
The Romney campaign did not immediately respond to a question about whether it would cease using the slogan.
Already this week Mr. Romney has stopped mentioning Glen Doherty, a former Navy SEAL killed in the attack on an American consulate annex in Benghazi, Libya, after Mr. Doherty's mother objected to the candidate politicizing her son's death.
The “Friday Night Lights†television show, about a high school football team, won critical acclaim and passionate fans, but low ratings during its five seasons on NBC, ending last year. Mr. Romney, who doesn't name the show, embraced the “Clear Eyes†slogan at the first presidential debate, where it appeared on a sign in his backstage waiting area.
Shortly after, Mr. Romney began using it at rallies, usually after describing a 14-year-old boy he had befriended and counseled as he was dying of leukemia. He said the bo y's bravery in facing death reminded him of the slogan, which in the show is chanted by players in the locker room as inspiration before a game.
Mr. Romney also wove the phrase into accounts of others he knew who had died tragically. “This is something that we share in this country; men and women of clear eyes and full hearts, and America can't lose,†he said in one speech.
“I was not thrilled when I saw that you have plagiarized this expression to support your campaign by using it on posters, your Facebook page and as part of your stump speeches,†Mr. Berg wrote in his letter.
Mr. Berg does not seem to have the kind of legal case that musicians invoke when insisting political candidates stop playing their songs, an increasingly common phenomenon, especially for Republicans, dating from at least when Bruce Springsteen objected to Ronald Reagan's use of “Born in the U.S.A.â€
A rapper, K'naan, threatened legal action over the Romney campaign' s use of “Wavin' Flag†at rallies, and a co-writer of “Eye of the Tiger'' filed a suit against Newt Gingrich.
But Mr. Romney has one vote of support connected to “Friday Night Lights.†Buzz Bissinger, the author of the classic nonfiction book that inspired the television series, announced that he would vote for Mr. Romney in a column on The Daily Beast on Oct. 8, declaring that he was a life-long Democrat who was swayed by Mr. Romney's debate performance.
A version of this article appeared in print on 10/13/2012, on page A13 of the NewYork edition with the headline: TV Show Creator Complains to Romney.