WASHINGTON (REUTERS) - Republican National Committee chairman Reince Priebus urged Republicans on Thursday not to appear on MSNBC shows because of a tweet from the network that said "the rightwing" might disapprove of a Cheerios television ad featuring a biracial family.
Mr Priebus sent a letter to MSNBC president Phil Griffin demanding an apology.
The cable news network's tweet on Wednesday said, "Maybe the rightwing will hate it, but everyone else will go awww: the adorable new #Cheerios ad w/ biracial family" to promote an MSNBC story on the breakfast cereal commercial, which will be broadcast during Sunday's Super Bowl.
The ad stars Grace Colbert, 6, as the daughter of a fictional biracial couple. Last year, she was in a similar Cheerios commercial, which triggered racist comments when it was posted on YouTube, Google Inc's video-sharing site.
MSNBC executive editor Richard Wolffe went on Twitter to denounce his network's original tweet as "dumb, offensive", and said it had been taken down. "That's not who we are at msnbc," he tweeted.
In his letter to Mr Griffin, Mr Priebus said the Cheerios tweet showed that MSNBC "is poisoned by this pattern of behaviour".
"Sadly, such petty and demeaning attacks have become a pattern at your network," Mr Priebus said. "With increasing frequency many of your hosts have personally denigrated Americans - especially conservative and Republican Americans - without even attempting further meaningful political dialogue."
Until he gets an apology, Mr Priebus said RNC staffers were banned from appearing on MSNBC, seen by critics as favouring the left, and he urged other Republicans to stay away as well.
"Phil Griffin is the head of MSNBC and the buck stops with him," said an email from RNC headquarters. "There have been too many of these incidents on too many of his shows to allow subordinates to continue issuing one-off apologies. It's time for Mr Griffin to take responsibility for his network's toxic programming and take corrective action."
Earlier this month, MSNBC host Melissa Harris-Perry apologised on the air for a segment that joked about the adopted black grandson of Mr Mitt Romney, the Republicans' unsuccessful 2012 presidential candidate.
The segment featured a photo of Romney and his wife with their grandchildren and members of a panel were asked to suggest captions. Mr Romney later accepted her apology.
Actress Pia Glenn sang that "one of these things is not like the others", and comedian Dean Obeidallah joked that the photo "really sums up the diversity of the Republican Party".
MSNBC is owned by Comcast Corp.