"When you take on people who have an enormous amount of power you do not win on your first shot," Vermont Senator and former Democratic presidential candidate Bernie Sanders tells BBC Hardtalk's Stephen Sackur.

In a recent battle for the new chairman of the California Democratic Party - the biggest democratic party in the US - the Bernie Sanders progressive candidate lost to the party's establishment candidate.

But Mr Sanders argues the movement has not lost.

"Is the momentum with us? Damn right it is," he said, adding that political revolution does not happen overnight.

Watch the full interview on BBC World News and the BBC News Channel on Monday 5 June 2017.