GetUp has been forced to amend its instruction guide for volunteers after the activist group's boss was caught in an embarrassing interview in which he was unable to justify claims that Treasurer Josh Frydenberg was "part of the coup" against Malcolm Turnbull.

National director Paul Oosting had defended a GetUp instruction manual that suggested volunteers tell voters Mr Frydenberg was "part of the coup that removed Malcolm Turnbull as prime minister", even if he might be "a nice person".

Awkward encounter: GetUp's national director Paul Oosting. Credit:Alex Ellinghausen

GetUp - which has amassed a donations war chest of $12.5 million in the past year - has now scrapped references to the coup in its guide for volunteers in Mr Frydenberg's electorate, and instead says the deputy Liberal leader was "part of the chaos in Canberra".

There has been no evidence Mr Frydenberg played an active role in the push to oust Mr Turnbull. He did not support Home Affairs Minister Peter Dutton's tilt for the top job - he voted for Mr Turnbull in the first leadership spill and remained in cabinet while Mr Dutton’s backers quit.