Nick Clegg describes words of Brown and Cameron as 'a smokescreen for the truth'
Nick Clegg has said that voting either Labour or Conservative would be a "vote for corrupt politics".
Speaking at a press conference in central London, the Liberal Democrats leader said his party was the only one committed to cleaning up politics.
He highlighted Lib Dem plans to bring in proportional representation (PR), and the power to sack corrupt MPs.
Labour is proposing a referendum on whether to introduce a form of PR for future general elections.
Gordon Brown is due to talk about this later on Wednesday, as part of the party's plans for wider constitutional reform.
This is expected to include highlighting his commitment to a fully-elected House of Lords.
The Conservatives propose enabling constituents to remove their MP if he or she is found guilty of wrongdoing.
On Wednesday, Mr Clegg continued to refuse to say whether he would back Labour or the Conservatives in a hung parliament.
"How we govern this country is not my choice, not Gordon Brown's , and not David Cameron's - it is the choice of the 45 million people entitled to vote in this election," he said.
What we have been saying is you can't pretend to people, you can't treat people as idiots - when money is tight you can't have something for nothing
In the result of a hung parliament, he added that "then of course politicians will need to talk to each other to provide the stable government this country needs".
Mr Clegg said that in such a situation, the party that gained the most seats had "the moral right, the first right to seek to form a government".
He also refused to be drawn on whether he would decline to back a minority Labour administration if Gordon Brown remained as prime minister.
Speaking earlier to the BBC's Radio 4's Today programme, he said he did not want to get into a "parlour game of 'what if' politics".
But he added that if the Lib Dems join any future government, they would seek tax reform.
The party's central tax policy is to increase the threshold at which people start paying income tax to £10,000, which it says would mean almost four million people on low incomes no longer having to pay any income tax.
It also wants to close tax loopholes that it says benefit the wealthiest members of the population.
Saying both Labour and the Conservatives wished to prevent change, Mr Clegg said the Lib Dems were the only party "campaigning for radical reform".
He said the Lib Dems also wished to reform the House of Lords, and the system of party donations.
Turning to the Lib Dems' policy on reducing the public deficit, Mr Clegg said the party had identified an additional £15bn of spending cuts on top of those targeted by Labour.
The party's proposed measures to reduce the deficit included a £400 cap on pay increases in the public sector, a 10% levy on banking profits, and ending the £250 child trust fund.
He said that such measures were better than the alternative of raising VAT.
"What we have been saying is you can't pretend to people, you can't treat people as idiots - when money is tight you can't have something for nothing," he said.
When questioned on his party's continuing support for the UK adopting the euro, Mr Clegg admitted that "eurozone interest rates over the last few years would have been wrong for Britain".
He said the euro was "not for now" but added that "we think there is a case for, a long-term case for, considering entry into the euro, which needs to be done with a referendum".
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