Addressing a "Rally for Jobs" on the opening day of his party conference in Glasgow, the LibDem leader delivered a criticism of the mindset within David Cameron's party.
The speech coincided with a poll commissioned by the Tory peer Lord Ashcroft suggesting Labour will win the next general election thanks to a lead in key marginal seats.
Portraying the LibDems as a brake on Tory excesses in government, Clegg told delegates: "The Conservatives have a bizarre idea that to create more jobs you need to increase insecurity.
"They aren't the Party of Jobs. They are the Party of Fire At Will.
"Remember that? A proposal for bosses to get rid of staff no questions asked. A policy dreamed up by a Conservative donor without a shred of evidence to back it up. So we said no.
"But let's be in no doubt that without us taking a stand in government it would have happened. Without us job security would have been a thing of the past, with employers able to get rid of staff on a whim."
The Deputy Prime Minister also said that some Tories thought private sector jobs were inherently of more merit than those in the public sector, such as teaching and nursing.
"But we know that you shouldn't divide public and private sector workers as if only jobs in the private sector matter.
"The truth is that in both the public and private sectors people have made sacrifices: longer hours, more flexibility, pay freezes, to protect jobs. So we should be praising all of this country's workers, public and private sector, for the determination they have shown in tough economic times."
Clegg also criticised Labour, saying he would take them more seriously only if they apologised for their mistakes in office.
"Apologise for being too busy schmoozing the bankers to worry about the risks they were taking with the economy. Apologise for not balancing the books in the good times. Apologise for abolishing the 10p tax rate."
Attacking the Tories is risky for Clegg. The more he suggests they are monsters without the LibDems, the more voters may question why the LibDems keep them in power at all.
Glasgow SNP MSP Bill Kidd said: "After previous betrayals on issues like tuition fees south of the Border, the LibDems only have themselves to blame for becoming a party that people simply cannot trust."