US President Barack Obama said Wednesday that it is "possible" that the Republican candidate Donald Trump is his successor, and warned that the tycoon lacks "basic knowledge" about the world and "does not seem interested learning"."Everything is possible," Obama said when asked about the possibility of a Trump presidency,"What I think is scary is a president who does not know what to know and to have no interest in learning what you do not know," said the president.Obama said in his press conferences and debates, Trump has shown a lack of "a basic knowledge about the world or about what a nuclear triad, or where several countries, or the difference between Sunnis and Shiites in the Muslim world are "."Those are things he does not know and does not seem to have spent much time trying to learn" about them, Obama said.In the same vein, US Vice President, Joe Biden, said today that Trump "knows nothing about foreign policy" and not try to surround himself with "people who know" about the Republican Party.