"I will never support the Tory idea that you cut taxes for millionaires and the benefits somehow trickle down. That's not what struggling families need. They need their money back."
And he said offering tax cuts at the next election for struggling middle and low income families would mark the Lib Dems out as the only party committed to social justice, describing their plan as the most "progressive and redistributive" ever put forward by a British political party.
He also mounted a sustained attack on the government, saying: "They are so desperate to protect their own jobs, they can't be bothered to protect other people's."
"They are a zombie government."
Mr Clegg also turned his fire on David Cameron, accusing the Tory leader of "arrogance" and "born-to-rule conceit" and his party of not being able to come up with any concrete policies.
"Cameron's hope is to become the Andrex puppy of British politics. A cuddly symbol, perhaps.
"But fundamentally irrelevant to the product he's promoting," said Mr Clegg.
On wider economic issues, he called for tougher regulation of the banking system, saying a "firestorm" was spreading through the financial sector, and for measures to prevent people having their homes repossessed.
He called for increased investment in alternative sources of energy as the backbone of a "new, green economy" and reiterated the party's opposition to new nuclear and coal-fired power stations.
The truth is Lib Dem sums don't add up. They offer a menu without prices
Angela Eagle, Labour
Turning to the public services, he called for billions to be spent on improving educational opportunities for the most disadvantaged and for patients to have more control over the care they receive.
He ended by pledging to "transform politics" with fewer MPs and an end to big donations and "fiddled expenses".
And in a bold echo of a former leadership speech by David Steel, pledged that the party was on the road to government, saying it would take "a giant leap forward" towards its goal of doubling its number of MPs at the next election.
The party currently has 66 MPs - the highest total in its history, but recent opinion polls suggest its support has not significantly increased since the last general election.
'Out of touch'
Opposition parties criticised the Lib Dems' tax policy, to be partly funded by billions of pounds in efficiency savings in public spending, as unclear and unrealistic.
Labour said Mr Clegg was "out of touch" with ordinary people after he was forced onto the defensive on the eve of his first major party conference speech when he mistakenly said that the weekly state pension was "about 30 quid", a third of its actual value.
Treasury Minister Angela Eagle said: "The truth is Lib Dem sums don't add up. They offer a menu without prices."
The Lib Dems have also come under fire over their plan to cold call 250,000 voters with an automated message to get feedback on Mr Clegg's key policy promises.
The SNP accused the party of "hypocrisy" as it had been criticised by the Lib Dems for using automated calls.
But Lib Dem Chief Executive Lord Rennard insisted the calls were for market research purposes and not party propaganda.
The Information Commissioner's office said it was "concerned" about the plan but could not stop parties carrying out market research.
A spokesman added that they had contacted the Lib Dems to "clarify the nature of the calls" but had not yet seen the proposed script.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.