CHICAGO: President Barack Obama wiped away tears as he paid tribute to his teenage daughters and to Michelle Obama, his "best friend," at the emotional close of a farewell address in his adoptive city of Chicago Tuesday. 

"Michelle LaVaughn Robinson, girl of the south side, for the past 25 years, you have not only been my wife and mother of my children, you have been my best friend," Obama told the first lady, seated before him dressed all in black.

"You took on a role you didn't ask for and made it your own with grace and grit and style and good humor," he told her, at one point pulling out a handkerchief to dab away tears -- as the crowd of 18,000 cheered wildly.

"A new generation sets its sights higher because it has you as a role model. You've made me proud. You've made the country proud."

It was in Chicago that the Obamas met, that their daughters were born, and as the president put it in a Facebook post ahead of the speech, "for Michelle and me, Chicago is where it all started."

While 18-year-old Malia was there to hear her father's farewell speech, her 15-year-old sister Sasha was not -- the most notable of a series of public absences by the teen that prompted a flurry of good natured chatter on social media, and a hashtag #SashaObama.

A White House official said Sasha stayed back in DC tonight because she has an exam at school in the morning.

But Obama addressed both girls in praising the "two amazing young women" they had become, during the family's eight years in the White House.

"Of all that I have done in my life, I am most proud to be your dad," he said -- as Malia, dressed in black-and-white, shed a few tears with her mother's arm around her.

"You are smart, and you are beautiful, but more importantly, you are kind, and you are thoughtful, and you are full of passion," Obama told them. "And you bore the burden of years in the spotlight so easily."

And finally, the 55-year-old president turned to Joe Biden -- who along with his wife Jill he described as a second "family," drawing yet another standing ovation for the vice-president.

"You were the first decision I made as a nominee, and it was the best," Obama told Biden. "Not just because you have been a great vice president, but because in the bargain, I gained a brother."

After the president's speech drew to a close, the Obamas and their daughter came together on stage for a warm embrace.

-AFP