We're just nine days away from what many believe to be the most uncertain election outcome in living memory. And with the polls showing no clear majority, a hung parliament is looking increasingly likely.
This could lead us towards another coalition government, or its more obscure friend "confidence and supply", which is a much less formal alternative.
It's not a regular arrangement. In fact the most recent time it was used was back in 1977, when the Labour government made a deal with the Lib Dems after it was left with no overall majority in the face of a by-election defeat. It hobbled on for a year before collapsing, owing to an ambiguity in the contract.
So what is it?
This is a scenario in which a larger party governs by making a confidence and supply agreement with a smaller party (or parties). While this kind of arrangement is often weaker than a coalition government, it does tend to be more predictable than a minority government.
And there are two distinct elements. The first is "confidence" - implying support for or abstinence from any votes of no confidence, which could threaten to topple the government.
The other is "supply" which refers to voting through the Budget.
But why would the smaller party (or parties) sign up for this? Generally, the larger party will agree to enact elements of its smaller ally's manifesto.
At the same time, they get the opportunity to benefit from elevated power without the risk of being tainted by its role coalition government, which - as evidenced by the Lib Dems' current state - can become unpopular.
Why does it matter?
The prospect of a confidence and supply government is being touted in the run-up to this General Election because neither Labour nor the Tories look likely to secure an outright majority.
The latest YouGov polls put the two main parties Labour and the Tories at 35 per cent and 34 per cent respectively. They're followed by Ukip with 12 per cent, the Lib Dems with nine per cent and the Greens at five per cent.
What are the possible scenarios?
We could see David Cameron put forward a confidence and supply deal to the Lib Dems or Ukip (or both).
And while Ed Miliband could theoretically make a similar offer to the Lib Dems, he's ruled it out for the SNP.