Tina is the embattled politician's best friend. She offers him comfort and support when he is under fire, and shields him from his most persistent critics. She helps him shut down debate.

Tina - "There is no alternative" - was coined by Margaret Thatcher in the 1980s to justify her economic policies. In recent days, however, it is the Liberal Democrats who have embraced the mantra. Despite their drubbing in the Scottish and local elections - "a total bloodbath", in the words of a Lib Dem frontbencher - the party has consciously and collectively decided not to rock the boat. The coalition will continue, say Lib Dems, though the relationship will be less "chummy" and more "transactional" and "businesslike". I asked a senior and loyal Lib Dem peer whether such changes would make a difference. "Well, there's no alternative, is there?" he replied gloomily.

When a politician claims there is no alternative, there tends to be one, if not several. The Lib Dems have plenty of options. For a start, their coalition with the Tories can continue - but it doesn't have to continue in its current form. As I have argued before, the obvious alternative to the coalition's "pooled" ministries, containing senior and junior ministers from different parties, is "segregated" ministries containing only ministers from a single party. As Catherine Haddon of the Institute for Government has pointed out: "Segregated minis­tries allow parties to clearly present their policy achievements to the electorate."

Wonky worries

Nick Clegg's biggest mistake was to try to make the Lib Dems "own" the whole coalition, rather than divide up responsibility for particular areas. They have therefore struggled to "present their policy achievements", which explains all the chatter these days about the need for "differentiation" from the Tories. Another Lib Dem mistake was to concede all the great offices of state - the Treasury, Home Office and Foreign Office - as well as the big-spending departments - Health, Education, Work and Pensions - to the Conservatives.

If David Cameron, as is expected, sacks the Tory Health Secretary, Andrew Lansley, in the next cabinet reshuffle, the Lib Dems should
insist on taking full, "segregated" control of the Department of Health. It would be the ideal opportunity to show the country that the NHS is safe in Lib Dem, and not Tory, hands.

Clegg and his colleagues, however, prefer to focus on issues such as social mobility, civil liberties and Lords reform. These are distractions. "Social mobility" is a wonkish phrase that has little resonance with the public; the Tory Justice Secretary, Ken Clarke, is taking most of the credit for progress on civil liberties; and Lords reform is a bizarre issue for the Lib Dems to focus on, given the result of the Alternative Vote referendum and lack of public enthusiasm for constitutional reform. Even the party's activists aren't impressed. "I'm so not bothered about Lords reform," says Richard Grayson, the Lib Dems' former director of policy. "It's so pathetic to believe that it can be some sort of sop to us." As he points out: "The fundamental problem for our party is that there isn't any differentiation between us and the Tories on the central political issue of our time: the deficit."

The Liberal Democrats, having performed a U-turn on the pace and depth of fiscal retrenchment upon receiving the keys to their ministerial cars last May, now need to focus on restraining the Tories' zeal for reckless spending cuts. Last October, Chris Huhne, the Lib Dem Energy Secretary, said the proposed cuts were not "lashed to the mast". He needs to remind his colleague Danny Alexander, the coalition's axeman-in-chief, of this.

Then there is the question of Nick Clegg. The Lib Dems should ask themselves: is it time to ditch their leader? Questioning Clegg's leadership is taboo inside the party, with senior Lib Dems adamant that his position is secure. "Changing the leader would be bonkers," says a frontbencher.

Would it? Some would argue that a change of leader would be a step towards the Lib Dems winning back "permission to be heard" on a wide range of issues. In modern politics, the messenger matters as much as the message. Voters dislike and distrust Clegg. He is reviled - and not just by students who have hanged effigies of him. Nearly two in three voters over 40 couldn't find anything positive to say about the Deputy Prime Minister, according to a recent YouGov poll. Does anyone seriously believe that Cleggphobia can become Cleggmania again? Unless, say, he saves a drowning child between now and May 2015, it's highly unlikely.

Dump Tina

But will there be a challenge? A senior Lib Dem source describes Clegg's front-bench colleagues as "spineless", and Tim Farron, the centre-left party president, has said he is "standing shoulder-to-shoulder with Nick Clegg". But if the Lib Dems are serious about reducing the level of chumminess in the coalition, then Clegg is a problem. He is the public face of the Tory-Lib Dem love-in: TweedleClegg to TweedleCam. He admitted to Jemima Khan in this magazine last month that he has played tennis with "Dave". He told Cameron after a joint Q&A session with voters in Nottingham in March: "If we keep doing this we won't find anything to bloody disagree on in the bloody TV debates." Without disagreement, however, the Lib Dems are politically dead.

But why would the Tories allow the smaller party to tinker with a coalition agreement that is serving the bigger party so well? Conventional wisdom says that the Lib Dems have no leverage because the Tories, in the ascendancy, could call a snap general election in which Clegg's party would be wiped out. Perhaps. But why not call the Conservatives' bluff? George Osborne, the electoral genius who couldn't secure a majority for his party against the most unpopular prime minister in living memory, doesn't want a general election any time soon. Growth has stalled and the cuts are only now beginning to kick in.

Meanwhile, the Boundary Commission, charged with merging and redrawing constituencies, and reducing Labour's inbuilt electoral advantage, is not due to report until September 2013. And if the local council election results were replicated in a general election held tomorrow, Labour would win a majority of 18.

The Tories don't want an election yet. The Lib Dems, though bruised, still hold a strong card. It's time to ditch Tina.