Trump advisor: Campaign will be ‘dirtiest ever’
Media playback is unsupported on your device
Video

Trump advisor: Campaign will be ‘dirtiest ever'

US political consultant and commentator Roger Stone learned his trade in the Nixon White House. Now he advises Donald Trump in his campaign to win the US presidency.

He talks to James Naughtie about phone calls with Mr Trump, the appeal he has to voters and the tone of his campaign.