cheerios-superbowl-commercial-lg*MSNBC lowered the boom on an employee who sent out a controversial tweet about the Cheerios Super Bowl ad  featuring a biracial family.

The full tweet, sent at 8:06 p.m. from MSNBC’s official Twitter account, read: “Maybe the rightwing will hate it, but everyone else will go awww: the adorable new #Cheerios ad w/biracial family.” The tweet prompted Republican National Committee chairman Reince Priebus to call for a Republican boycott of the network.

In a statement issued Thursday afternoon, MSNBC president Phil Griffin called the tweet “outrageous and unacceptable” and said the employee who sent it has been “dismissed.”

“We immediately acknowledged that it was offensive and wrong, apologized, and deleted it,” the statement continued. “We have dismissed the person responsible for the tweet. I personally apologize to Mr. Priebus and to everyone offended. At MSNBC we believe in passionate, strong debate about the issues and we invite voices from all sides to participate. That will never change.”

MSNBC anchor Ari Melber read Griffin’s statement at the end of the network’s 3 p.m. hour.

The Cheerios ad is the second spot to feature a biracial couple and their daughter, “Gracie.” When General Mills premiered the first spot last May, social media exploded with racist comments. The company disabled the comments section on the ad’s YouTube site, though the spot also received much praise.

Priebus sent a letter Thursday morning to Griffin denouncing what he characterized as “demeaning attacks” that “have become a pattern” at MSNBC.

“With increasing frequency many of your hosts have personally denigrated and demeaned Americans — especially conservative and Republican Americans — without even attempting to further meaningful political dialogue,” wrote the RNC chairman.

It is the latest mea culpa for MSNBC, which has already parted ways with Martin Bashir and Alec Baldwin, while weekend host Melissa Harris-Perry issued a tearful apology for her comments regarding Mitt Romney’s adopted African-American grandson.

In an e-mail to “interested parties,” RNC communications director Sean Spicer, noted that Priebus and Griffin spoke by phone on Thursday. “We appreciate Mr. Griffin’s admission that their comment was demeaning and disgusting, and the Chairman accepted his apology,” wrote Spicer, adding that the RNC “will aggressively monitor the network to see whether their pattern of unacceptable behavior actually changes.”

He continued: “We don’t expect their liberal bias to change, but we will call them out when political commentary devolves into personal and belittling attacks.”