In his last major speech to the party before the general election, Mr Clegg said the single-figure opinion poll ratings did not reflect the picture in battleground seats where the Lib Dems were able to mount an effective campaign.
He also launched a fresh attack on his Conservative coalition colleagues, saying “cows moo, dogs bark and Tories cut – it’s in their DNA”.
Accusing them of an “ideological lurch to the right”, he said: “They have gone from being the self-proclaimed heirs to Blair to Nigel Farage in white tie.”
Labour’s plans would cost £70bn, he said as he mocked Ed Miliband’s “pledge card”.
“It’s not a pledge card, it’s a credit card,” he said. “And you, me and every other British taxpayer will be paying the bill for years to come.”
“If we want to remain an open, confident, outward-looking society, it will only happen if political parties who believe in compassion and tolerance step up to the plate,” he told the conference.
“Instead, the opposite is happening. Labour and the Conservatives are deserting the centre ground.
“Compromise is treated like a dirty word. Everywhere you look there is blame and division.”
Mr Clegg condemned the “angry nationalism” of Ukip, the “red-faced bluster” of the Tory right and the “scaremongering” of Labour.
He added: “Just like we would not put Ukip in charge of Europe, we are not going to put the SNP in charge of Britain – a country they want to rip apart. It’s just not going to happen.”
After years of austerity, Mr Clegg insisted there was “light at the end of the tunnel” but only if the Lib Dems are in power.
“David Cameron and Ed Miliband are not offering light at the end of the tunnel,” he said. “They are not offering hope.
“They are in a defensive crouch, hoping to win by default, not because the British people share their vision but because they dislike them a little less than the other guy.”