Doing the deal
Why, I was asked, might it be difficult for the Lib Dems and the Tories to reach agreement? Because, I replied, they are opponents.
Indeed, across large swathes of England, Scotland and Wales, they are visceral enemies.
There will be Tories who are choking at the prospect of a deal with the Liberals - as they always style them.
Namby-pamby, pussy-footing, "say anything to get elected", find me a fence and I'll sit on it. You can just hear them.
Then again, they can probably swallow their angst in order to get David Cameron into Downing Street after thirteen years of opposition.
Bit more challenging for the Lib Dems. Unless they get serious movement on political reform - a cross-party commission is very far from serious - then a full-scale coalition would be difficult to sell to their members.
The sandal-wearing propensity in the Lib Dems is now, sadly, in decline. Far, far too many suits. But there is a doughty gang who would be willing to get the old footwear out, socks optional, if Nick Clegg signs up to a deal that does not include a firm route map towards PR.
Bung Scotland into the mix and this is a notably tricky ask for the Lib Dems. Would you really want to be Tavish Scott, going into Holyrood elections on a programme of progressive change while his Westminster colleagues are in coalition with the Tories?
You remember the Tories? Used to be a big force in Scotland? Came fourth at this election north of the Border? Still stuck on a single seat? Yes, that's them.
Mr Scott would, I suspect, find it rather uncomfortable to be pushing the message of reform while his opponents drown out his offering with taunts that his party is a wholly owned subsidiary of the Conservatives.
I know, I know, Scotland is different. The Lib Dems are quite entitled to take different perspectives north and south of the Border.
Do you think that would stop Mr Scott's opponents, Labour and Nationalist, from delivering the jibe?
Talking of the Nationalists, just why is Alex Salmond pushing a "progressive coalition" so avidly?
For one thing, he favours that outcome. For another, it gives him potential relevance in the post-election haggling.
Incidentally, not sure it was entirely wise of Labour in Scotland to heap such scorn on the prospect of involving the SNP. Yes, guys, you loathe Mr Salmond. I get the concept. But have a wee glance at the Commons arithmetic.
Plus - contrary to some Labour claims - he was not making it up when he said his party had been approached to sound them out; he was not making it up when he confirmed that the SNP had held preliminary talks with civil servants.
No more, no less.
But back to the main question. Why is Mr Salmond pursuing this? Politically, it adds to the pressure on the Scottish LibDems, arguing that there is an alternative which they reject "at their peril", to quote Angus Robertson.
Further, a coalition deal which excluded the Tories would, presumably, infuriate the Right-wing press and the voters of England who backed the Tories more than other parties.
At a stroke, you highlight Scotland's political difference and you oblige the voters of England to put up with the form of electoral mismatch which has, more commonly, affected Scotland. Potentially putting strain on the Union.
For a Nationalist, what's not to like?
Most likely outcome? Tipping towards coalition. But, perhaps, more probably an arrangement whereby the LibDems support the Tories on confidence motions and "supply" (that's money to you and me).
Nick Clegg would bill this as putting Britain's interests first while sustaining a modicum of independence for his party. Tavish Scott would like that.