Barack Obama rose to power as the country's first African American president with message of hope and boundless optimism for the future.

"If there is anyone out there who still doubts that America is a place where all things are possible...who still questions the power of our democracy, tonight is your answer," he told crowds in Chicago in 2008 after winning the election.

In all the years since he never wavered from his mission to help foster in America what he once called the "renewal of morality".