Election 2015: Would a Tory government create chaos?
Instability, uncertainty, chaos. Could those words - used again and again by David Cameron to describe the prospect of a minority Labour government propped up by the SNP - apply to a minority Tory government riven by divisions about Europe?
That's a question I put to the prime minister.
Q: If you go back into No 10 on Friday, aren't we guaranteed two years of uncertainty about Britain's most important economic relationship - our membership of the EU? If that isn't chaos and instability, what is?
A: "Well the right thing to do with Europe is to have a strategy and a plan for securing Britain's future and that is what I have. I'm saying let's renegotiate, get a better deal that's put to the British people in an In/Out referendum… We've had so many treaties, we've had so many powers passed to Brussels, it's now time to make a change, have a better approach for Britain in Europe and for the British people to decide."
I suggested that "we've seen this movie before" in the 1990s when John Major was PM and there was a war between John Redwood and Ken Clarke. The Tory leader told me that this time would be different because the row then was about whether to have a referendum at all.
What, though, is his Plan B if he can't persuade EU leaders to give him the better deal he says he wants, or if the British people reject it? It's a question I've asked him before - at last year's Conservative Party Conference - but he is no nearer to giving an answer.
If you don't get the deal and you don't get the referendum? What's plan B for Britain?
"I'm confident we will get the deal."
What's Plan B?
"Well, I've demonstrated. People said you'll never cut the EU budget, I cut it. People said you'll never veto a treaty, I vetoed a treaty. So people know with me, I have a strong record of negotiating in Europe."
But what is Plan B?
"Well, Plan B is to hold a referendum. And for the British people to choose...
Plan B is you don't know.
"I do know."
You may have a negotiation you can't succeed in and a vote that you lose and Britain will be out of the EU.
"The only thing you have to be clear about is to have a plan for the changes you want, which I've been clear about. The referendum that then takes place, and I've said I'm confident I'll get those changes and I will recommend Britain stays in a reformed European Union and people know that that is my aim, that is my goal.
'Heads in sand'
"But the real point here, Nick, is if you don't have a plan for Europe, Britain will just drift towards the exit. The other parties are sticking their head in the sand thinking this issue will go away. It won't. It's time for some decisive action, some decisive leadership."
The prime minister is much clearer, though, about the fact that he will not "bargain away" his promise of a referendum if the Conservatives "fall short" of securing a majority at the election.
You've been pretty clear that without a referendum you don't want to be PM… Are you saying "I would rather Ed Miliband was prime minister, I would rather Labour ran the country, than stay on as PM without a guaranteed EU referendum"?
"What I am saying is that people would worry that were we to fall short - and I don't believe we will - this is something that could be bargained away and I want to be absolutely clear with people that that will not happen… Come what may, I will not be PM of a government that does not deliver that referendum."
I also asked David Cameron about the alleged chaos, instability and uncertainty he says will be created if he doesn't win. The Tory campaign has obsessed about the SNP for two reasons: first because the party's success against Labour in Scotland could help ensure that the Tories become the largest party in the UK and, secondly, because fear of the influence of a powerful group of Scottish nationalists in Westminster is, according to insiders in all parties, shifting votes in England.
Without the rise of Nicola Sturgeon, David Cameron would already be packing his bags… you are utterly dependent on them doing well for your own personal survival?
"I don't accept that. The Conservatives have one seat in Scotland, we are hoping to add to that what's happening in Scotland, or looks like it's going to happen in Scotland, is a calamity for Labour and that's not my responsibility."
Today, in language that no other politician would dare to use, Boris Johnson escalated the Tory warnings about the SNP, talking of "Ajockalypse now". Mr Cameron told me that "Boris has his own way, very colourful descriptions and I leave those to Boris".
But his language, talk of puppets, illegitimacy. Are you not threatening the future of your own country to preserve your own job?
"No, I'm saying that the best way to save the country is to have a government that would work for the whole of the UK, that is not reliant on nationalists from one part of it, and that is a Conservative majority government. I am fighting the SNP with everything I've got. I totally disagree with them about their plan to break up the UK.
"This potential alliance of people wanting to break up the country, of people wanting to bankrupt the country, is incredibly dangerous for our country and that's why I'm warning so vigorously if people have got four days to stop it. I've got the answer: If you vote Conservative, it won't happen."
Of course, no-one knows the outcome of an election that has yet to take place but minority government of one flavour or another looks quite likely and, whether it's led by Ed Miliband or David Cameron, it will raise some pretty profound questions about the future of the country.