Mr Clegg said 2009 tested his faith in politics
Nick Clegg has said political leaders must show voters their "convictions", in the run-up to the general election.
In his New Year's message, the Lib Dem leader said they must do more than talk of "dividing lines" or in sound bites.
He said voters did not want politicians "clinging on to power for its own sake" or telling them what they want to hear.
Mr Clegg also criticised the culture of Prime Minister's Questions, with MPs "yelling and guffawing at each other as if the outside world didn't exist".
Mr Clegg, leader of the UK's third biggest political party, said his own belief in politics had been tested "to breaking point" in 2009.
Punch and Judy
"I remember once looking round the House of Commons during another Punch and Judy session of Prime Minister's Questions," he said.
At the time he said youth unemployment had just reached its highest level ever, soldiers were fighting in Afghanistan and the economy was in the middle of "the worst recession in generations".
"And what were the politicians doing? Yelling and guffawing at each other as if the outside world didn't exist. So I don't blame anyone for feeling a sense of despair about our clapped-out political system."
Mr Clegg said, as the "countdown to the next general election finally begins", he wanted to ask his rival party leaders what they believed in.
"People don't want leading politicians clinging on to power for its own sake, or just telling people what they want to hear. There's got to be more to it than that...
"If we as leaders want people to turn out to vote at all at the next general election, we have got to show people our convictions, not just dividing lines, our beliefs, not just sound bites."
He accused Labour and the Conservatives of learning to "parrot the language of change" but of opposing cleaning up party political funding and of changing the voting system.
Prime Minister Gordon Brown must call a general election by June 2010 at the latest.