Your biggest decision in a generation: Cameron issues rallying cry to voters as Tories take a three-point lead... but one in six are STILL undecided 

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Britain faces its ‘most important decision in a generation’ at the polls tomorrow, according to David Cameron.

In a last-minute appeal today to wavering Ukip and Lib Dem voters, the Prime Minister will insist only the Tories can secure the economic recovery and thwart a dangerous Labour-SNP alliance.

He says there is only ‘one choice – me or Ed Miliband as prime minister propped up by the SNP’.

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The Tories have taken a three-point lead over the Labour party who have slipped back in the polls 

Prime Minister David Cameron warned the electorate that Labour can on only govern by dealing with the SNP

Ed Miliband, pictured, plans to govern with a left-wing coalition despite not having the largest party 

He will add: ‘Ed Miliband knows that as things stand he can only become prime minister with SNP support.

‘But he won’t say that or explain it. The British people are not fooled. That’s why it keeps coming up on the doorstep.’ As a poll for the Daily Mail last night showed the Tories have opened up a three-point lead just 24 hours before the polls open at 7am:

• Ed Miliband and Neil Kinnock conceded Labour might not win the election – but began setting out plans to seize power;
• The Labour leader claimed he would not borrow more than the Tories – even though independent economists say he would load £90billion on to the national debt;
• George Osborne warned that investors could take fright on ‘fallout Friday’ at the prospect of a Labour government.

The ComRes survey suggests crucial momentum lies with David Cameron’s party, who are on 35 per cent to Labour’s 32 per cent. Last week, the pollster had the two main parties tied.

But 15 per cent – nearly one in six – of those who said they are likely or very likely to vote are still completely undecided.

The poll will lift Tory spirits in the closing hours of the campaign – suggesting they are on course to be the largest party again. However, the lead is nowhere near big enough for a Conservative majority.

Ukip is on 14 per cent according to this latest opinion poll with leader Nigel Farage unlikely to win his seat

Lib Dem leader Nick Clegg, pictured, warned without his party the country will have another election in 2015

Ukip is on 14 per cent, the Lib Dems on 9 per cent and the Greens on 4 per cent. Katharine Peacock of ComRes said: ‘The polls have remained remarkably consistent over the course of the campaign. Despite the TV debates, manifesto launches and policy announcements nothing seems to be shifting the dial.’

Mr Cameron will say Britons are about to ‘make their most important decision for a generation: me as your prime minister continuing the plan that’s put the country on the right track. Or risking it all with Ed Miliband, held to ransom by Nicola Sturgeon, Alex Salmond and the SNP.’ He will add: ‘I warn you: a vote for Ukip or the Lib Dems opens the back door to a Labour government: It will result in Ed Miliband as prime minister, unable to survive without SNP support.

‘And that support will cost you money. They will take us back to square one, with heavy borrowing and higher taxes for more welfare. An economy facing ruin.’

Yesterday, Tory HQ deployed Boris Johnson to appear with Mr Cameron and warn that Mr Miliband wants to drag the country back to a ‘French version of the 1970s’.

The London Mayor said: ‘Never have I been so worried about what will happen under Labour. Their basic message seems to be don’t invest, don’t compete, don’t create, don’t strive, don’t bother to build your enterprise to create jobs.’

Mr Clegg warned Britain faces a second general election by Christmas unless the Lib Dems are part of the next government.

Mr Miliband will today tell supporters: ‘We are more determined than ever to set out the choice facing working people. We know that Britain only succeeds when working families succeed.’