Now is the time for Liberal Democrat MPs to come to the aid of their party – and the country. They should turn their backs on the coalition and join forces with the Labour opposition in order to oust David Cameron from power.

This is just the right moment to unseat a prime minister who has forfeited his right to the office. The string of policy U-turns previously indicated that he is devoid of political touch. But his lack of judgment has been acutely exposed in relation to the phone-hacking scandal.

He ignored advice to the contrary by making Andy Coulson, the disgraced former editor of the News of the World, his communications chief. He compounded the error by inviting Coulson to Chequers after he had resigned.

He has been exposed as indulging in far too cosy a relationship with Rupert Murdoch and, most particularly, the former News International chief executive and erstwhile NoW editor, Rebekah Brooks.

He avoided attending the key Commons debate on hacking and the future of BSkyB, rightly being accused of failing to show proper leadership.

He watched the Met police chief Paul Stephenson fall on his sword. Yet he is surely more at fault than Stephenson, who hired a former NoW deputy editor, Neil Wallis, who was not, at that time, publicly linked to the hacking scandal.

Moreover, that sensational turn of events occurred while Cameron was abroad because, despite the all-consuming domestic political crisis engendered by hacking, he went off on an ill-timed trip to Africa.

He has belatedly decided to cut his visit short, but – as with so many of his decisions – his change of mind only confirms his lack of political nous and tin ear for what really concerns the British public.

To be honest, Cameron is damaged goods. He dithers and he dissembles. And the mud will stick because this story isn't going to go away in the coming months, even years, because of the various inquiries.

Meanwhile, the people of Britain are growing more and more sceptical about Cameron's relationship with Murdoch's News Corporation.

Lib Dems cannot be other than aware of their disastrous electoral performance ever since they went into coalition with the Tories. And they will be conscious of the likelihood that their party will lose many seats at the next general election if they continue to be identified as junior partners of an increasingly unpopular government.

However, if they were to make a principled stand on the topic that is in the forefront of the public's mind – the phone-hacking scandal and the associated cover up – they stand a better chance of retaining, and even enhancing, their electoral support.

In current circumstances, by tipping Cameron from power, the Lib Dems could be viewed as acting in the wider public interest. They could achieve this quite simply by agreeing to support – or, even more boldly, by tabling – a Commons motion stating that the house no longer had confidence in the prime minister.

It would place the party on the side of the angels. It would restore public confidence in its independence. It would create the conditions for an election in which nervous Lib Dem MPs might well prosper.

If Nick Clegg is to rescue his credibility, he must lead his Lib Dem troops into anti-Cameron action as soon as possible. Carpe diem.

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