Ed Miliband promised today to publish details of his private meetings with major Labour donors as he renewed his call for an independent inquiry into allegations that Conservative supporters were offered access to the Prime Minister in return for cash.
David Cameron revealed yesterday the names of 17 Tory donors who had been invited to dine with him at Downing Street or Chequers since he became Prime Minister in 2010.
The Prime Minister gave in to intense pressure to expose the meetings with wealthy benefactors - between them thought to have given the Tories £23 million since 2005 - after party co-treasurer Peter Cruddas was caught promising meetings and influence in return for cash.
Mr Miliband is now expected to release details of private meetings with major donors since he became Labour leader by the end of this week.
"I'm very happy to publish and to be very transparent about what we do and who we meet," said Mr Miliband.
"But what I do say is let's be realistic about what happened here. We've got an issue about the way in which government is being conducted, the way in which Downing Street is being used.
"That is, I think, what concerned people: Downing Street, Chequers, the way that those Government buildings have been used.
"That is why we need not just proper transparency from the Government, but we also need a proper inquiry, an independent inquiry into what happened."
Mr Cameron's promise of a party inquiry into the Cruddas affair, chaired by Tory peer Lord Gold, was denounced by Labour yesterday as a "whitewash".
They have called for an independent investigation by the Prime Minister's official adviser on ministerial interests, Sir Alex Allan.
Former justice secretary Jack Straw called on the Electoral Commission today to investigate suggestions that foreign donations could be channelled through a third party to escape rules outlawing overseas cash.
Donations are only legal if they come from individuals on the electoral roll or from companies registered in the UK.
Sarah Southern, a former Conservative Party staffer now working as a lobbyist, was recorded by the Sunday Times saying: "The party will look at the criteria of which... in that document you'll have seen the kind of the legal bullet points and as long as the money is coming from a legal UK-registered donor, or a legal registered UK company that is operating, then they'll normally be happy."
In a letter to the watchdog, Mr Straw wrote: "According to reports, undercover reporters told Mr Cruddas and Ms Southern that they were interested in making a donation on behalf of Middle Eastern donors.
"The reporters were allegedly told that money from foreign investors could be channelled through a company established by the reporters as they were on the UK electoral roll."
He added: "These reports raise serious questions as to how the Conservative Party is soliciting donations, potentially in contravention of the Political Parties, Elections and Referendums Act 2000."
As opinion polls suggested the Conservatives were losing support over the issue, senior party figures tried to turn attention instead to the wider question of political funding.
Cross-party talks are expected to be reopened this week in a fresh attempt to end the deadlock which has stymied attempts to reduce the influence of big donors for many years.
Mr Cruddas was caught on film telling undercover reporters that "premier league" gifts could secure meetings with ministers and influence policy.
He quit his post on Saturday, hours after the Sunday Times revealed his comments.
Mr Miliband will have been further buoyed by an opinion poll which showed the opposition racing into a double-digit lead amid the fallout from the controversy and last week's unpopular Budget.
Two-thirds of voters agreed that tax changes announced by Chancellor George Osborne last week show his was "the party of the rich", according to the ComRes research for The Independent.
The poll puts Labour up three points over the last month on 43%, with the Tories down four at 33% and the Liberal Democrats down two on 11%. Others gained three points to 13%.
But among the third of voters who were polled after the Cruddas story emerged, the lead had widened to 17%. Other polls also showed a growing Labour lead.
All three main parties have named two members to handle negotiations over party funding, which the minister in charge - Deputy Prime Minister Nick Clegg - said he hoped would start this week.
Mr Cameron said there was an "urgent need" for wider reform and he would back a £50,000 cap on individual donations - but only if Labour agreed to apply it to trade unions.
That is the stalemate which has seen a succession of attempted shake-ups fail but options are also limited as parties are agreed there is no appetite for increased state funding.