By Mike Sergeant
Political correspondent, BBC News
Nick Clegg knows the stakes could not be higher for his party and the country
"A deliciously painful torture mechanism".
That's what the voters have given the Liberal Democrats, according to former leader Lord Ashdown.
Given what he said in the campaign, Nick Clegg felt he had no option but to allow the Tories first crack at forming a government. He always maintained the party with the most votes and seats would have the "moral authority" to try.
But, if that party had been Labour rather than the Conservatives, a deal might already have been done.
On a whole range of issues - tax, the economy, political reform, Europe - Labour and the Liberal Democrats make much more comfortable partners.
On the ground during the election campaign, most of the really tough bare-knuckle fights came between the Lib Dems and the Tories - principally in the south west of England.
Now Nick Clegg is asking the very same people who've been trying to bite chunks out of their Conservative opponents to cuddle up to them, and hand David Cameron the keys to Downing Street.
Excitement and concern
This makes many Liberal Democrats feel nauseous to say the least. But there's also an excitement within the party. The election result has given them their first serious sniff of power for 90 years.
The crushing disappointment of election night - after such a memorable campaign - can be quickly forgotten. The Liberal Democrats, at last, have what they've craved for so long: relevance.
Most senior figures within the party acknowledge the awkward opportunity they've been given. Many of their hearts say Labour. But, given the situation they're in, their heads say the Tories.
Areas of common ground are emerging - on deficit reduction, education, bank regulation, and some aspects of political reform. But a referendum on changing the voting system could still be a deal breaker.
"Of course there's a lot of pressure from the grassroots. Some say don't do a deal with the Tories," one very senior Lib Dem MP told me.
"But some say don't do a deal with Labour. In the end we just have to do what's right".
The Liberal Democrats are under real pressure to show that post-election negotiations can work. If they get what they're after, and the voting system is changed, an outright winner becomes much less likely in all future elections.
The scenes we've witnessed over the last couple of days - of tight-lipped teams, and their advisers rushing between secret meetings - could become the norm.
If these talks collapse amid acrimony it will undermine the very thing the Lib Dems are arguing for inside the negotiating room: collaborative politics.
But, some senior Liberal Democrats have always said that differences between their party and the Conservatives might be "irreconcilable".
So, the possibility remains of switching quickly to Plan B (a Labour pact, possibly with the Scottish and Welsh Nationalists) if Plan A doesn't work out.
An arrangement with Labour, though, would also be hugely problematic. If Gordon Brown remains, they get accused of propping up a beaten prime minister, and forging a "coalition of the defeated".
If Gordon Brown goes, then an unelected leader might once again be prime minister.
Would the electorate stand a situation where none of the three men who fought the campaign (and battled it out in the TV debates) ended up with the top job?
There are serious questions about the viability of a Liberal Democrat-Labour alliance. For a start, the two parties together simply don't have enough seats to secure a majority in the House of Commons.
All sides say they want "stable government" at the end of all this. Given the wider economic and financial situation, a short term fix won't be good enough.
But securing that and keeping his party on-board is now the ultimate test of Mr Clegg's political skill.