Chicago : US President Barack Obama today asked Americans to unite and protect the country’s democracy which he said is being threatened by racism, inequality and a corrosive political environment as he made his farewell speech after eight years in the White House.

“Democracy can buckle when we give in to fear. So just as we, as citizens, must remain vigilant against external aggression, we must guard against a weakening of the values that make us who we are,” Obama, 55, said in his address to the nation from his home town here.

The 55-year-old outgoing President lamented that despite his historic election as the nation’s first black president in 2008, “race remains a potent and often divisive force in our society.”

“After my election, there was talk of a post-racial America. Such a vision, however well-intended, was never realistic,” he acknowledged.

Obama’s presidency will come to an end on January 20 when Republican Donald Trump would be sworn in as the 45th President of the US.