"Let me say something about my wife," Obama said during a campaign event in Iowa.
"I don't usually like to follow her speaking. Because let's face it, on the charisma rankings in my household, you've got her, the girls, Bo and then my mother-in-law and then me," Obama said to laughter.
Obama realised what he had said and was quick to say his mother-in-law Marian Robinson was actually more charismatic than the dog, the Huffington Post reported.
He quickly corrected himself and bumped Bo, the family pet Portugese water dog, down a notch, below his mother-in-law. For good measure, he also praised his mother-in-law lavishly to make ammends for the gaffe.
"Actually, my mother-in-law is before Bo, obviously," Obama said.
"I love my mother-in-law, too -- that's where Michelle got her looks from," he added.
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Robinson, lives with the family in the White House after Obama became the first American president to appoint a 'First Grandmother' in 2008 to look after his daughters.
But perhaps Bo, who is never far from the political limelight, is Obama's favoured companion in the White House.
The First Dog was a gift from Senator Edward Kennedy and his wife to Obama's daughters Sasha, 11, and Malia, 14, who had been promised a dog by their father when he was on the presidential campaign trail in 2008.
Obama is seeking a second term as the US President in the Noverber 6 elections and will be facing Republican rival, Mitt Romney in the contest.