By Justin Parkinson BBC News political reporter, in Bournemouth
Mr Clegg is facing his first autumn conference as leader
Britain is "watching the death throes of the Labour Party", Liberal Democrat leader Nick Clegg has said.
Speaking at the start of his party's annual conference, he added that Gordon Brown's government meant nothing to "the vast majority of British people".
The comments came after seven Labour MPs called for a leadership contest. Mr Clegg also called the Conservative Party "cowboys".
The conference, taking place in Bournemouth, lasts until Wednesday.
'Arrogance'
Mr Clegg, who became leader in December last year, will be closely scrutinised by party supporters worried about a "squeeze" on support by an improved Conservative showing in the opinion polls.
He also attacked the Tories at a Lib Dem rally, accusing leader David Cameron of "arrogance".
Mr Clegg added: "Here's a man who'll speak fondly of 'hardworking families' but has no actual plans to help them.
"A man who - with recession looming - puts millionaires first. A man who hopes that soundbites can fix the economy...
"If you want real solutions for Britain's economy are you really going to trust this bunch of Conservative cowboys?"
This will be seen as a retort to the Conservative leader's recent description of Mr Clegg as a "joke".
Of Labour, Mr Clegg said: "I do not think there is any way back for them.
"They no longer stand for anything that the vast majority of British people need or want".
'People's bills'
The Lib Dems were now "emerging as the only progressive party speaking up for people who want something different and something better", he added.
Delegates in Bournemouth have voted to introduce "people's bills", where the six legislative proposals which receive the most petition signatures are guaranteed a debate in Parliament.
They also called for a constitutional convention "to review and improve the governance of the UK".
The main theme of this year's conference is the party's plan to cut taxation for the poorest and its stated ambition to reduce the level of public spending by �20bn.
Other subjects up for debate include cutting crime, allowing more standing at football matches and how to respond to the effects of the credit crunch.
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