As broken on prweek.com on Tuesday, Harris has quit CCO as marketing director after just nine months. He will continue in the short term to act as an unpaid consultant to the party.
Howard appointed Harris alongside party co-chairman Maurice Saatchi and press secretary Guy Black after he won the party leadership last autumn.
According to sources close to the party, Harris became increasingly sidelined at CCO with his responsibilities gradually stripped away.
Over recent months, the research function has been handed to George Brydges, a former private secretary to John Major, while the operations department under Gavin Barwell took on his campaigning remit.
CSR consultancy founder Steve Hilton – a co-ordinator for the party’s successful 1992 election campaign – has been assisting with its advertising and marketing strategy as an adviser to Saatchi.
Harris was the brains behind the Tory’s ‘Let Down by Labour’ ads for the recent local and European election campaigns.
He also devised a competition inviting the advertising community and the public to create an ad for the party.
But his innovations have not helped lift the Tories from their mediocre showing in the opinion polls.
Harris gets married later this week and plans to finish his book on the phenomenon of text messaging when he returns from his honeymoon next month.
He said: ‘My future is in the commercial world, not the political world.’
The party will later this month reveal the first significant redesign of its torch logo since it was introduced during Margaret Thatcher’s premiership in the 1980s.