Downing Street and the Labour party have sought to play down speculation of a rift between Gordon Brown and Harriet Harman over the proxy donor row.
Ms Harman's position appeared unstable earlier in the week when the prime minister appeared reluctant to fully state his confidence in his deputy.
The prime minister's official spokesman insisted Mr Brown remains "fully supportive" of Ms Harman.
Ms Harman, deputy leader of the Labour party, has been accused of inadvertently implicating Mr Brown in the latest party funding row, after it emerged Mr Brown's campaign team had recommended Ms Harman consider a donation from Janet Kidd.
Last weekend it emerged Ms Kidd was one of the four intermediaries used by property developer David Abrahams to anonymously donate to the Labour party.
The Metropolitan police are now investigating why Labour failed to declare that Mr Abrahams donated more than £650,000 to the Labour party through proxies.
Under electoral law, the details of all donors must be recorded even if they gift money through third-parties.
Peter Watt, the now-former secretary general of the Labour party, resigned promptly on Monday after admitting he had failed to comply with electoral law.
The proxy donor row was dragged into the Cabinet when it emerged a number of candidates in the summer leadership campaign were offered funds emanating from Mr Abrahams.
Mr Brown and Hilary Benn's election teams rejected cheques signed by Mr Abrahams' conduits but Ms Harman went on to accept £5,000 from Ms Kidd.
This has cast doubt over official claims only Mr Watt and Labour's chief fundraiser Jon Mendelsohn were aware Mr Abrahams was anonymously bankrolling the party.
Last night, in a potentially damaging revelation, it emerged a member of Mr Brown's own campaign team passed on Ms Kidd's name to the cash-strapped Harman camp.
Labour MP Chris Leslie, who worked on Mr Brown's leadership campaign, confirmed he had been approached by Mr Abrahams in May to tell him Ms Kidd wanted to donate to the campaign.
Her donation was eventually rejected because Ms Kidd was not known to anyone within the Brown camp.
Mr Leslie was then approached by Ms Harman's team, who needed to clear their debts after her successful campaign for the deputy leadership.
He said: "I was approached by members of Harriet Harman's campaign team asking if I knew of any individuals who might donate to her deputy leadership campaign.
"I passed them the details of Ms Kidd as someone whose offer of a donation we had not taken up.
"The prime minister and Jack Straw were at no stage involved in, or aware of, the contact from Mr Abrahams or the offered donation from Mrs Kidd, as it was not my practice to discuss with them offers of donations which we did not intend to take up."
Nevertheless, Ms Harman has been accused of dragging the prime minister into the row.
Asked if she had "dropped him in it," Ms Harman said this was "absolutely" not the case.
She told reporters today: "I strongly maintain I have complied with the letter and spirit of the law and I think Gordon Brown has done the same."
With a criminal inquiry now underway to determine who knew donations were coming in to the Labour party through third-parties, Mr Straw continued to defend the prime minister.
He told BBC Radio 4's Today programme: "Gordon Brown had absolutely no knowledge of any connection - inappropriate connection - between Mr Abrahams and Mrs Kidd. Neither did I."
Mr Straw said 99.9 per cent of people in the Labour party were not involved in the latest funding row.
He continued: "If Gordon Brown had had even a sniff that this was going on, he would have stopped it immediately, as would have I."
Mr Straw - who oversaw the introduction of laws designed to clean up the party funding process in 2000 - said the latest scandal was "mindblowing" and "a matter of not just profound irritation but profound anger."
Meanwhile, with senior figures within the Labour party seemingly checking their own financial arrangements, Peter Hain has confirmed he failed to register a £5,000 donation to his own deputy leadership campaign.
He blamed an "administrative error" for his failure to list a personal gift from Mr Mendelsohn.