Besides Abraham Lincoln, President Barack Obama looks up to Mahatma Gandhi and Nelson Mandela as his heroes for bringing about transformative change without violence by changing people's minds and hearts.

"Abraham Lincoln is probably the President who I find most compelling because not only did he deal with probably the biggest crisis in American history, the Civil War, but he also did so in a way that was full of understanding of humanity," he told Russian state-run Rossiya TV and ITAR-TASS news agency.