U.S. Rep. Jim Sensenbrenner, second from left, seen in 2005, apologized on Thursday for saying Michelle Obama had a "large posterior." Reuters

U.S. Rep. Jim Sensenbrenner, R-Wis., sent an apology letter to First Lady Michelle Obama on Thursday after he was overheard talking about her large posterior.

Sensenbrenner faced a deluge of criticism after FishbowlDC reported on an overheard phone conversation in the Delta Crown lounge at Reagan International Airport, in which the congressman complained that the first lady lectures us on eating right while she has a large posterior herself.

He was referring to Michelle Obama's advocacy for programs that combat childhood obesity. Among other things, Obama has promoted the Let's Move initiative and a new federal nutritional guideline called MyPlate, which is intended to replace the traditional food pyramid.

Amanda Infield, a spokeswoman for Sensenbrenner, said on Wednesday that the congressman regretted his choice of words but doesn't think the government should be telling Americans what to eat. She added, While he may not agree with all of her initiatives, he plans to contact the first lady's office to apologize for his comments.

Sensenbrenner himself released a statement on Thursday, which said, I regret my inappropriate comment and I have sent a personal note to the first lady apologizing.

The first lady's office declined to comment on the incident.