The MP for Barrow-in-Furness John Woodcock has resigned from the Labour Party.
He will continue to stand as an independent.
Mr Woodcock has represented the Cumbrian seat since 2010.
He was suspended in April over claims he sent inappropriate messages to a former female member of staff.
He has denied the claim, which is being investigated by Labour, saying the allegation was "politically motivated".
A Labour spokesperson said:
“Jeremy thanks John for his service to the Labour Party.”