Clegg warns party: it will be a tough election

Leader speaks of 'golden opportunity' as former Tory MEP joins Liberal Democrats

Nick Clegg warned the Liberal Democrats last night that they faced the "biggest fight of our political lives" in the general election.

In a rallying speech, he insisted that the contest, expected on 6 May, was "still wide open". The Liberal Democrat leader said the public mood was more volatile than ever, presenting the party with a golden opportunity to break through.

He told its spring conference in Birmingham: "The people still haven't made up their minds. All bets are off. This government knows it has come to the end of the road. The Tories know people have started to see through them. And voters know the Liberal Democrats offer something different."

He added: "Don't think it's going to be easy. It's going to be tough. Tougher than anything we've ever done, because the closer we get the harder our opponents will fight to keep us down."

The party faces a daunting task in defending its 63 parliamentary constituencies, with many rural and suburban seats in the south and south-west of England under pressure from David Cameron's Conservatives. But the Liberal Democrats hope southern losses will be outweighed by gains from Labour in urban seats in the north.

The party received an eve-of-conference boost yesterday when a former Conservative European MP joined the Liberal Democrats over David Cameron's stance on Europe. Edward McMillan-Scott, once leader of the Conservative MEP faction in the European Parliament, rebelled against Mr Cameron's decision to quit the centre-right European People's Party grouping in the parliament. Mr McMillan-Scott had been expelled from the party six months ago. He said: "In Nick Clegg they [the Liberal Democrats] have a leader I like, admire and respect. They are internationalists, not nationalists. From being a liberal Conservative I become a conservative Liberal. Most of my family are liberals: I am pleased to join the Liberal family."

The party unveiled its general election slogan yesterday: "Change That Works For You. Building A Fairer Britain". Danny Alexander, Mr Clegg's chief of staff, explained: "This election will be about fairness and change and the Liberal Democrats are the only party that will deliver both."

Vince Cable, the treasury spokesman, warned that the party needed to demonstrate it was "fiscally responsible". He accused the Tories of trying to frighten people into voting for them by claiming a hung parliament would create panic in the City. "Playing fast and loose with the financial stability of this country for political gain – destabilising the markets – is dangerous, irresponsible and wrong," Mr Cable said.

Earlier Mr Clegg vowed there would be "no backroom deals" with other parties. As disclosed by The Independent this week, he has set four tests for Labour and the Conservatives if they are to seek his party's support in a hung Parliament. He said whichever party had the clearer mandate from the voters would have the "moral right" to govern "either on its own or with others".

The new Lib Dem logo

*Designers did not rush to embrace the Liberal Democrats' election logo as a classic, denouncing it as, variously, ugly, dull, limp, confusing, and guilty of Magpie-esque lifting of a supermarket logo and the Labour and Tory slogans ("A future fair for all" and "Year for change", respectively). The party declined to comment.