The Government must take action to clean up political funding before another "scandal intervenes", a Commons committee urged today.
MPs called on the Coalition to stick to pledges to reform party financing "in order to remove big money from politics".
Last year a 15-month inquiry by the Committee on Standards in Public Life proposed a £10,000 cap on donations in a bid to end "cash for influence" scandals and corruption allegations - partly paid for by a £23 million-a-year taxpayer subsidy.
But the three biggest parties united to rule out asking voters to pay up in the present economic climate - even if the change was delayed until 2015.
Although the Lib Dems are supportive of reforming party funding, Labour and the Tories can't agree because of their links to the trade unions and big business.
Labour - which is nearly £10m in debt - relies on union funding for the majority of its income. The Conservatives receive large donations from wealthy individuals in the City, something neither party appears willing to change.
The Political and Constitutional Reform committee concedes that a cross-party solution "will not be easy to achieve" but called on the Government to look again at the proposals.
"Public confidence in politics risks being further undermined if some future scandal intervenes before a solution is in place," its report warns.
Committee chairman Graham Allen said: "Public concern about party political funding continues to undermine confidence in politics and MPs.
"It is high time this issue was resolved. The publication of the report of the committee on Standards in Public Life provides a golden opportunity for the Government to get this issue back out of the box marked 'too difficult' and make a serious effort to find a fair solution which is acceptable to all parties."