David Cameron and Ed Miliband traded furious insults in one of their fieriest ever confrontations at Prime Minister's Questions, as the Labour leader fought to regain the initiative on party funding after a fortnight of damaging headlines over alleged ballot-rigging in Falkirk.
Mr Miliband branded the Tories a "party of privilege" funded by a handful of millionaires, while the Prime Minister retorted that Labour was owned "lock, stock and block vote" by the trade unions.
The Labour leader challenged Mr Cameron to accept his proposals for a £5,000 cap on donations to political parties and a limit on MPs' earnings from second jobs, and accused the Tories of handing a £145 million budget tax break to hedge funds which have donated more than £25 million to the party.
And he said that Labour would take action, if returned to power at the 2015 general election, to ensure that no MP was able to take on a new paid directorship or consultancy.
But Mr Cameron derided Labour's claim to the high ground, telling the Commons that all donations to his party were publicly declared, and warned that a cap could cost the taxpayer millions of pounds as state funding was used to fill the shortfall.
After seeing their leader suffer a mauling at last week's PMQs - when Mr Cameron submitted him to a ruthless barrage of barbs over Falkirk - the Labour benches kept up a deafening wall of sound during the angry exchanges, almost drowning out the Prime Minister on several occasions.
A succession of Labour MPs asked Mr Cameron about donations to the Tories, as Mr Miliband depicted the political battle as a choice between "the party of the people and the party of privilege".
Accusing Mr Cameron of "ducking reform", Mr Miliband said that union funding for Labour could not be compared with Tory reliance on wealthy individuals, telling MPs: "I will tell you what the difference is - 6p a week in affiliation fees from ordinary people up and down the country against a party funded by a few millionaires at the top."
The Conservative leader responded by accusing Mr Miliband of being in the pocket of union paymasters, telling MPs: "Here are the figures - £8 million from Unite, £4 million from GMB, £4 million from Unison.
"They have bought the policies, they have bought the candidates and they have bought the leader."