David Cameron has defended Conservative Party chairman Grant Shapps in the face of Labour demands for an i nvestigation in to claims he breached the codes of conduct for ministers and MPs.
Downing Street said the Prime Minister continues to have full confidence in Mr Shapps, after it was disclosed that he continued working as a marketer of get-rich-quick schemes under the pseudonym Michael Green after entering Parliament - something he had emphatically denied only weeks ago.
But Labour's campaign chief Lucy Powell urged the PM to ask his Independent Adviser for Ministers' Interests, Sir Alex Allan, to investigate whether Mr Shapps had breached the code requirement for ministers to be "as open as possible to Parliament and the public". Ms Powell said Mr Shapps may also have breached the MPs' code, which requires MPs to act with "probity and integrity".
Liberal Democrats added their voice to criticism of Mr Shapps, with one source saying: "Perhaps it's time for David Cameron to finally 'get rid of the Green crap'?"
The Tory chairman, who attends Cabinet as minister without portfolio, last month denied that he had continued to work as an internet marketer after being elected in 2005, telling LBC radio: "To be absolutely clear I don't have a second job and I have never had a second job whilst being an MP. End of story."
But a recording obtained by The Guardian captures the MP in 2006 selling business self-help guide Stinking Rich 3 and claiming his products could make listeners a "ton of cash by Christmas".
Mr Shapps initially dismissed the issue as an "old story", but the Conservatives said that although the chairman had talked of his writing career having ended when he became an MP "in fact it ended shortly afterwards". The BBC later reported that Mr Shapps told its correspondent he had "screwed up" on dates and stated his case "over-firmly" in the LBC interview.
A Conservative party spokesman said: "Like many authors and journalists, Grant wrote with a pen name. This was completely transparent: his full name and biographical details were permanently published on the company's main website.
"Given that this was a decade ago, and was mentioned during the cut and thrust of an interview, he referenced that his writing career had ended when he became an MP, in fact it ended shortly afterwards."
In an online interview with the BuzzFeed website, Mr Cameron said: "Grant did have another job when he first became an MP and he declared that in the Register of Members' Interests which is what you are meant to do.
"But he obviously made a mistake by saying in some interviews that the work had stopped earlier than it had. He's put that right so I think we can put that behind him. He's doing a good job."
In a letter to Mr Cameron, Ms Powell said the Tory chairman had "serious questions to answer" over whether he misled the public about his business activities.
"Such serious allegations cannot be allowed to hang over a man who has serious and wide-ranging ministerial responsibilities and who will be running your election campaign and so it is essential that this matter is immediately investigated," she said.
"Without clear answers from you today, you will be guilty of demonstrating a disdain for decency and integrity in our public life."
Ms Powell cited Guardian reports that as recently as last November, Mr Shapps had used legal action to extract an apology from a constituent who had referred to his activities as Michael Green in an internet post, and who was required to make clear that they had taken place "prior to entering Parliament".
Asked whether Mr Cameron accepted that Mr Shapps's comment in his LBC interview was a mistake, rather than an attempt to mislead, the Prime Minister's spokesman said: "Grant has said it was a mistake and the Prime Minister absolutely accepts that."
The spokesman stressed that Mr Shapps's outside business activities had been recorded in the House of Commons Register of Members' Interests as required.
Mr Shapps used to run the HowToCorp website which featured get-rich-quick advice from supposedly successful businessmen Sebastian Fox and Michael Green. His register entries between 2005 and 2007 stated that he had a remunerated directorship and a registrable shareholding in How To Corp Ltd.
In the 2006 recording, the senior Tory, under the Green pseudonym, told a fellow entrepreneur that the guide "is not a cheap product, but it's a great internet marketing product".
Labour MP John Mann said Mr Shapps had "clearly failed" to meet the expected standard of openness and honesty and should lose his ministerial role.
"The Government made a big play after the expenses scandal of bringing back integrity to politics and this does the exact opposite," he told BBC Radio 4's Today.
"You can't have a government minister who isn't honest and breaches one of those standards.
"That's what the standards are there for. He has breached them and he should go as minister without portfolio."
Liberal Democrat campaign spokesman Lord Paddick said: "Grant Shapps has serious questions to answer and he must come clean about the use of his Michael Green alter-ego during his time in Parliament."