I have aged not Michelle: Obama

Philadelphia: US President Barack Obama on Thursday said that in eight years of his presidency he has aged but not his "brilliant wife" Michelle who continues to "inspire" the nation as the First Lady.

"Twelve years ago tonight, I addressed this convention for the very first time," Obama, 54, said as he started his address to the thousands of his party delegates, leaders and supporters in this American city.

He was referring to his address at the Democratic National Convention in Boston in 2004.

"You met my two little girls, Malia and Sasha now two amazing young women who just fill me with pride. You fell for my brilliant wife and partner Michelle, who's made me a better father and a better man; who's gone on to inspire our nation as First Lady; and who somehow hasn't aged a day," Obama said.

"I know the same can't be said for me. My girls remind me all the time. Wow, you've changed so much, daddy. And it's true I was so young that first time in Boston. Maybe a little nervous addressing such a big crowd," Obama said amidst laughter from the audience.

"But I was filled with faith; faith in America the generous, bighearted, hopeful country that made my story  indeed, all of our stories  possible," Obama added.