Vince Cable became the most senior Lib Dem to appear with the Labour leader, Ed Miliband, on Monday morning, pushing the case for a yes vote in next month's referendum on the voting system.
Cable sought to highlight the absurdity of the current system, saying that if the Strictly Come Dancing programme he once appeared on had been decided on first past the post, former Tory MP Ann Widdecombe would have been declared the undisputed best dancer in Britain.
He said: "The public there, and in many other ways, do understand run-offs, they do understand the basic principle of the alternative vote."
As the campaigns to change the voting system approach their halfway points, Cable teamed up with the Labour leader, former home secretary Alan Johnson and comedian Eddie Izzard as they pledged their support for the yes campaign.
The event started just minutes before a rival event for the no camp, featuring the prime minister, David Cameron, and former Labour home secretary Lord Reid.
Miliband acknowledged that AV was not a "magic remedy or a magic cure". "But it can make for a more accountable politics, a fairer politics and a politics with a different culture".
Cable said he was "delighted" to be on the platform for the yes campaign but also said he would like to see his leader, Nick Clegg, appear. Miliband has vetoed appearing alongside the Lib Dem leader, believing the appearance of Clegg would persuade more people to vote no in protest at his decisions since joining the coalition.
Speaking in public for the first time since his very public criticism of the prime minister's speech on immigration, Cable made light of the row, pointing out that Cameron was elected leader of the Conservative party under the AV system.
"If they had their choice of leader determined by first-past-the-post rather than an alternative vote system, I would now be conducting my amicable, businesslike coalition discussions on immigration with Mr David Davis," he said.
Cable dismissed it as "bizarre" claims by the no campaign that ditching first past the post would provide a boost to extremist parties.
He said: "One of the most bizarre arguments used in this campaign is that somehow or other the AV system will favour extremist parties like the BNP. It will do exactly the opposite.
"The people who run the BNP may not be very bright, but at least they have worked out what's in their self-interest, and their self-interest is in opposing the alternative vote because every MP has got to reach out and get a majority of their electorate. It's much more difficult for extremists to accomplish that."
Miliband, meanwhile dismissed another of the no campaign's suggestions – that switching from first-past-the-post to AV would lead to more coalitions or that it would involve expensive complex counting machines. The no campaign have made much of the cost of new technology to deal with a new voting system with new ballot cards, producing a report last week in which they showed the cost of running a general election would triple if there were a move to AV.
Miliband also chose to temper his one-time aggressive attitude towards Clegg, urging voters not to use the referendum as an opportunity to give Liberal Democrat leader a "kicking".
"The chance to send a message to this Conservative-led government lies in the elections that are taking place in English local government, in Scotland and Wales."
"This referendum is not about Nick Clegg, it's not about David Cameron, it's not about me. It is a chance to have a better politics in Britain.
"It is a chance to choose hope over fear. It is a chance to choose change over the status quo. I urge people to vote yes on 5 May."
Alan Johnson made his first appearance since leaving his role as shadow chancellor in Ed Miliband's shadow cabinet. Boris Johnson has been voluble against AV, but Johnson pointed out that the London mayor had been elected by an AV system. When Johnson was born, he pointed out 94% of voters went for one of two parties but at the last election that was down to 44% and so the system had to be changed.
Johnson also pointed out that Cameron's plan to elect police commissioners would see this new position elected by using the supplementary vote, similar to AV.
"I believe first-past-the-post should be left where it belongs on the race track."
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