2016 US presidential election candidates
Media playback is unsupported on your device

US election 2016: How have early frontrunners fared?

Thursday's Republican debate marks the first contest of the 2016 presidential campaign season - and the field is certainly crowded.

But both parties have their frontrunners, with Donald Trump on top for the Republicans and Hillary Clinton leading the Democrats.

However, history shows that those leading the polls 15 months before the election don't always stay on top.

So what's happened to those early leaders in the past?

Produced by the BBC's David Botti

  • 05 Aug 2015
Go to next video: 2016 Republican message mash-up