David Cameron has shared a platform with one of his party’s most vociferous critics as the battle over voting reform intensified.
The increasingly bitter campaign moved up a gear as Mr Cameron and Labour’s Ed Miliband made rival speeches for and against the alternative vote (AV).
There is less than three weeks to go until a referendum his held on whether AV should replace first-past-the-post.
The Prime Minister took the unprecedented step of teaming up with Labour’s former home secretary John Reid to support the “No to AV” campaign.
Mr Cameron said one of the few things on which he agrees with Lord Reid is that AV would be “wrong for Britain”.
He went on to appeal for people to listen to their gut instincts – saying AV is “obscure, unfair and expensive”.
“I believe in the principle of one person, one vote, and AV would mean that votes of some people get counted more than others,” he said.
“In a healthy, strong and robust democracy, power lies in the hands of people not the political elites.
“People vote politicians in, politicians are then responsible for what happens and, if things go wrong, people should be able to make politicians answer for it.
“And if people don’t like the answer, people should be able to kick those politicians out again.”
Elsewhere, Mr Miliband stood up alongside Business Secretary Vince Cable to back the “Yes” vote.
The Labour leader repeated his plea for the public not to view the referendum as a vote on personalities.
“This referendum is not about Nick Clegg, it’s not about David Cameron, it’s not about me,” he said.
“It is a chance to have a better politics in Britian. 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 May 5.”
Writing for The Independent newspaper, he earlier accused the “No” campaign of trying to frighten voters into keeping the status quo and described the referendum as a battle of “hope versus fear”.
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The party leaders had been expected to tone down their language after accusations of mudslinging and dirty tactics over the weekend.
Unlikely inter-party alliances have formed against a backdrop of growing pressure over the AV poll, which is being held on May 5.
The UK-wide referendum was a key concession wrung from the Tories by the Lib Dems as part of the deal to join them in a power-sharing administration after last year’s General Election.
Speaking to Sky News on Sunday, Mr Cameron insisted the coalition was in no way jeopardised by the vote.
But it threatens to provoke a serious backlash among the backbenchers of whichever of the two parties loses out, amid more and more vitriolic exchanges between senior figures.
Many Conservatives feel changing the voting system would be a disaster for their party.
Many MPs risk losing their seats under the system and argue Mr Cameron should never have agreed to the referendum.
Meanwhile, former Lib Dem leader Paddy Ashdown launched a bitter attack on George Osborne, claiming he and other anti-AV campaigners had engaged in “smears, deliberate misrepresentations and sometimes even downright lies”.
The presence of Mr Cable alongside the Labour leader is certain to fuel further speculation about the future of the partnership.
Despite Mr Miliband’s support for the AV cause, many of his MPs and peers – including several senior figures – are lined up against him.
In his Independent article, he said: “There is a real danger that this opportunity will be lost if people do not vote on the merits of this issue.
“People from all parties should look beyond personality or political affiliation. It isn’t often that every person in the country gets a direct opportunity to reshape our politics.”
Absent from today’s proceedings was Deputy Prime Minister Nick Clegg – with whom Mr Miliband has refused to share a platform over fears his presence could deter backers.
The latest opinion poll at the weekend suggested public attitudes were hardening against AV, giving the “no” camp a six-point lead, an exact reversal of the position in January.