This is the most outlandish theory of how the Conservatives could form the next government

If the Conservatives fail to secure enough seats to form a government in May's General Election, but still get the highest overall number of seats they could make an offer to the Scottish nationalists in order to remain in power, according to one theory being passed around in closed circles and local media.

The thinking goes something like this: At the moment, the Conservatives look to be on track to secure between 270-280 seats on May 7. That would leave them around 50 seats short of the 326 seats they need to form a majority government.

Conventional wisdom at the moment has the Conservatives doing a deal with the Liberal Democrats (who are on course to secure around 25 seats) and the Democratic Unionist Party (projected to win 8 seats). That, however, would still leave the Tories well short of the seats required and could force the party to allow Ed Miliband's Labour party to try to form a functioning government.

So what to do? One option is to do a deal with the SNP.

On the face of it, such a deal sounds perverse. The majority of the Conservatives electoral campaign has been devoted to telling the country about the chaos that would emerge from doing deals with the Scottish nationalists. But the appeal of holding onto office and making a Labour majority a much more difficult task in future, may sway a few within Tory ranks.

Here's how such a deal would work: The Tories could offer the SNP what it so desperately wants - the ability to control all tax and spending policies in Scotland. This would require some painful negotiations over, for example, North Sea oil revenues and no doubt a review of the Barnett formula under which transfers from Westminster to devolved administrations in Scotland, Wales, and Northern Ireland are worked out.

However, in return the Conservatives could simply request that the SNP follow Sinn Féin's example and refuse to take its seats in Westminster after May. That would leave around 50 seats empty, meaning that a government could be formed with only 300 seats (e.g. within the current forecast of a Conservative/Lib Dem coalition).

And it's not only tempting from a short-term political perspective. There are many in the Conservative ranks who have become frustrated with the sword of Damocles being held over the UK by the SNP's refusal to rule out another referendum vote. Granting effectively full autonomy to Scotland within the union could do much to blunt that threat as well as ensuring that the Conservatives' push for "English votes for English laws" - in response to the much criticised "vow" of devolving more powers to Scotland made in last year's independence referendum campaign - becomes a de facto reality.

Some people are already convinced that it could happen. Iain Martin, editor of CapX and Telegraph commentator, argues that it's not merely possible but likely that such a deal will be put on the table:

If Tories biggest party + SNP wipeout Lab will be astonished if Tories don't offer big deal. Eng voting. Fiscal autonomy. Good luck Scotland

- Iain Martin (@iainmartin1) April 19, 2015

A big mistake the Nats make is to think Tory Party is still old-style Unionist. Masses of interest among Tory MPs in a federal settlement.

- Iain Martin (@iainmartin1) April 19, 2015

There are, however, plenty of reasons to question the appeal of such a Hail Mary attempt to form a government.

Firstly, it assumes that the SNP voter base is more interested in fiscal autonomy than in sticking it to the Conservatives. That in itself seems a stretch. In last week's BBC debate, SNP leader Nicola Sturgeon seemed to slam the door shut on the possibility of any deal with the Conservatives telling the audience "I can guarantee that we get rid of a Tory government if you vote Labour."

Secondly, it imagines that the Conservative leadership can drag both the rest of the party in Westminster and its wider party membership down the road toward a more fractured union. Given that the party has endured one of its most rebellious parliaments since the Second World War with Conservative MPs voting against the government in 19% of divisions by 2013, the idea that it can be easily swayed seems rather optimistic.

Moreover, doing such a radical deal rather than allowing the "chaos" of a Labour/SNP government to fail by itself is likely to be read as a sign of weakness rather than a sound tactical move. With UKIP breathing down their necks in the South any sign that the David Cameron would be willing to retreat on his commitment to the union in order to secure power could act as a rallying cry for disgruntled Conservative MPs to follow Douglas Carswell and Mark Reckless in defecting to Nigel Farage's cause.

Though a Tory/SNP deal is highly unlikely, with so much about this election season a new experience for Britain, ruling anything out at this stage would be folly. Whatever happens, this is going to be a nail-biting ride to the finish.