Troubled times for Clegg and Co

After the initial thrill of seeing Liberal bums occupying ministerial seats for the first time since the wartime coalition of the 1940s, the past couple of months have proved something of a reality-check for Britain's third party.

First, there was the loss of their rising star David Laws from the coalition Cabinet after just 16 days following revelations in the Daily Telegraph about his expense claims and his private life.

Then the Climate Change Secretary, Chris Huhne, was forced to do a Robin Cook and swiftly dump his wife for his mistress after their affair was exposed by the News of the World.

Mr Huhne kept his job, although conspiracy theorists would doubtless see a pattern in this double embarrassment for key Liberal Democrats at the hands of Tory-supporting newspapers.

But of course, the unease currently being felt across Nick Clegg's party is not just about the personal difficulties of individual Lib Dem ministers. It goes much deeper than that.

The first two months of the coalition have been dominated by the Tory 'cuts' agenda, with Chancellor George Osborne emerging as the dominant figure in the government much as Gordon Brown did under Tony Blair.

For the Lib Dems, it has meant the humiliation of being forced to eat their pre-election words, when they warned that cutting too deep, too fast could cause another recession.

More and more grassroots Lib Dems, and even some of the party's more left-leaning MPs, have started to ask the question: What's in this for us?

Well, this week came the answer – news that a referendum on changing the voting system from first-past-the-post to the alternative vote is to be held next year, probably on 5 May.

For Deputy Prime Minister Mr Clegg, who will formally announce the move next week, it represents perhaps a once-in-a-lifetime chance to achieve the Lib Dem Holy Grail of electoral reform.

There are strong practical arguments for having the vote this early on in the Parliament, in that if it were held any later there would be little chance of getting any changes through in time for the next election.

Against that, though, is the obvious danger that it could shorten the coalition's life by about four years if the referendum is lost.

Were that to happen, of course, there would be little incentive left for the Lib Dems to remain in the government, and Mr Clegg would come under pressure from his party to obtain a swift divorce.

This might, in turn, provide a perverse incentive for the Conservatives not to campaign too hard against the change to AV, although premier David Cameron has insisted that he will.

The referendum poses a dilemma for Labour, too. The logic of opposition suggests it is in their interests to get a 'no' vote in order to try to bring down the government and force a 2011 election.

But many Labour MPs favour AV, and both Miliband brothers have made clear the party will campaign for a 'yes' vote if they win the leadership.

Whether or not Mr Clegg succeeds in his ambition will depend at least in part on whether the coalition can retain the broad popular support it currently holds.

As the North-East knows all too well, referenda held at a time when the government is unpopular tend to result in resounding 'no' votes.

The biggest danger for the 'yes' campaign is that the public comes to view this as an irrelevance when set against the economic problems facing the country – as many Tory MPs already do.

Not for the first time in recent months, the Lib Dems are finding themselves having to negotiate uncharted – and shark-infested – political waters.