SirKeir Starmer has been accused of 'deliberately avoiding' dealing with the row over Angela Rayner's two houses.
Labour's leader has still not seen the legal and tax advice his deputy received about her previous living arrangements, which have now been dramatically called into question by her former aide.
However his team has looked at the guidance and the matter is under investigation by police.
Asked yesterday why he was reluctant to look at it, Shadow Home Secretary Yvette Cooper said: 'Angela welcomes the opportunity to set out all of the facts, be it with the police, the HMRC or the appropriate authorities.
'I certainly wouldn't expect to see their personal advice about the personal finances of any of my colleagues.' Told it was 'puzzling' that Sir Keir had not seen the guidance, Ms Cooper insisted on Sky News: 'I think that's a perfectly reasonable thing for him to do.'
Angela Rayner at the Labour Party local elections campaign launch in Dudley. The deputy leader is being investigated by police after claims she may have broken electoral law
Sir Keir Starmer (pictured) has still not seen the legal and tax advice his deputy has received about her previous living arrangements as police re-open the decade old investigation
And pressed as to why he didn't 'acquaint himself with his own deputy's defence', she said: 'I think Keir has a very strong team around him, and rightly so, and that's why I think not only have they looked at this and been clear about it, but also Angela has as well.'
Last night Conservative Party chairman Richard Holden commented: 'Yvette Cooper confirmed Sir Keir Starmer still hasn't even looked at Angela Rayner's legal advice despite admitting his team have already seen it.
'It's crystal clear that he is deliberately avoiding dealing with this serious ethics scandal because he is too weak to lead.
'Rather than sniping from the sidelines, having spent weeks covering for Ms Rayner, it is time Sir Keir Starmer overcomes his weakness and launches an independent investigation into this whole situation so the public can know who is telling the truth and who knew what when.'
In another dramatic twist – after Greater Manchester Police announced on Friday that officers were opening a full investigation into the case – Ms Rayner's former chief adviser has come forward to contradict her account.
Matt Finnegan has given a statement to detectives saying that her actual home was in her then-husband's property, not her former council house where she was registered to vote.
He said he visited her at Mark Rayner's property in Lowndes Lane, Stockport, in the summer of 2014 just before she was selected as a Labour candidate.
'There was no doubt in my mind that this was Ms Rayner's family home, where she lived with her then husband Mark,' he wrote. His letter, quoted by The Sunday Times, went on: 'I remember it quite vividly because Ms Rayner was not at home at first and I had to wait for some time in my car before she eventually arrived.
The property on Lowndes Lane in Stockport, Greater Manchester is just one that the Labour deputy owned
Photos on estate agent Rightmove's website show the living room of the house Ms Rayner claims not to have been living in
'It was also memorable in that it was the first and only time I visited her home during the course of my voluntary work for her.'
His testimony could be important because if Ms Rayner was living in Lowndes Lane, it implies that she put incorrect information on the electoral register.
It would have also meant she was liable to pay up to £3,000 in capital gains tax when she sold her former council house in nearby Vicarage Road as it would have been her second property rather than her main home.
Ms Rayner has insisted the Vicarage Road house was her home – despite neighbours claiming she rented it to her brother – and that she has not broken any rules.
READ MORE:Police investigate Angela 'two homes' Rayner: Labour deputy under fresh pressure as detectives reopen election law probe into claims she registered at the wrong address - as party insists she broke no rules and remains 'absolutely 100%' behind her
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A Labour spokesman said: 'Angela has always made it clear that she also spent time at her husband's property when they had children and got married, as he did at hers.
'The house she owned remained her main home. Angela looks forward to sitting down with the appropriate authorities, including the police and HMRC, to set out the facts and draw a line under this matter.'
Labour's hopes of their deputy being cleared have been raised by the fact that nearly a decade has passed since she moved out of the properties and the police rarely pursue historic infringements of electoral law.
Giving false information is an offence under the Representation of the People Act 1983 but there is a time limit of a year for bringing any charge.
Magistrates can extend this in rare situations.
The investigation could also be hampered as the local council no longer holds key data, although the police would have access to information such as utility bills, credit checks and DVLA records.
Officers would also be expected to interview neighbours.
Last week The Mail on Sunday revealed dozens of online posts by Ms Rayner showing her life with her children and cats at her then husband's address.
One photo from the property she claims not to have lived at was even posted with the caption 'just got home'.
