Contested convention

Obama Could Play 'Trump' Card in Sanders Meeting
President eager to begin pitch to senator's 12 million primary voters

Bernie Sanders and President Barack Obama will sit down on Thursday. (Photo by Win McNamee/Getty Images)

President Barack Obama  is expected to take on a tough job on Thursday — trying to ensure that millions of Bernie Sanders supporters begin falling in behind presumptive Democratic presidential nominee Hillary Clinton.  

It will be difficult for Clinton to defeat Donald Trump without a large number of the 12 million people who have cast primary votes so far for the independent Vermont senator.