Once upon a time, long, long ago – well, six months ago – Nick Clegg gave a pre-election interview to the Observer in which he forecast "Greek-style" unrest on the streets of Britain if the next government tried to drive through policies for which it did not have a proper mandate. I thought at the time that this was over-the-top attention-seeking by a Lib Dem leader who was then struggling to make an impression on the consciousness of the nation. For this was before the leaders' TV debate which briefly transformed him into the messiah of a new politics.

I am now happy to admit that I was wrong and he was right. The government is facing street demonstrations with a Greek streak during which the protesters roar that they have been betrayed. What Nick Clegg didn't anticipate – where his crystal ball let him down – was that he would be the focus of the fury.

The student marches against the hike in tuition fees have seen violence done to a variety of targets: a police van trashed and windows smashed at Tory Towers. But it is about the Lib Dem leader that the protesters, the peaceful majority and the anarchic minority alike, are most venomous. The police have advised him to stop cycling for fear of his personal safety; excrement has been pushed through his letter box. The National Union of Students is hoping to mobilise its members in their greatest numbers to coincide with the Commons vote on the legislation this Thursday. The walls of Westminster will again reverberate to their chants, the least rude of which is: "Nick Clegg! Dick Head!"

In most governments with a highly contentious programme, there is a hate figure who arouses great anger in sections of the population. Before the election, many of us expected this position to be filled by George Osborne who seemed a natural for the role. He thought so himself. As it has turned out, the cunning chancellor has kept himself at one remove from the frontline by rationing his appearances to setpiece speeches, announcements and infrequent interviews. It is instead the Lib Dem leader, the erstwhile "nice Nick", who has become the lightning rod for discontent during the government's first significant trial of will.

That this should be over fees has come as something of a surprise both to members of the coalition and to the media. The future of higher education barely impinged on the national election campaign. As I recall, fees were not mentioned once in the 270 minutes of debating time between the leaders in the three TV debates. The Tories and Labour had struck a secret, pre-election, non-aggression pact not to press each other on the issue and to hide together behind the review conducted by John Browne. Both knew that if either came to power they would find themselves jacking up the fees. As for Mr Clegg, before the election, he had tried and failed to persuade his party to drop its pledge to abolish fees and adopt a more realistic position. Foolishly, Lib Dem candidates, himself included, nevertheless swore to abolish the fees that they are now proposing to hike. Extra stupidly, they even posed with pledge cards. It is for that pre-election opportunism that they are now paying a severe price.

Some of the defences mounted by senior Lib Dems for their volte face are reasonably persuasive. They have brokered a policy – one in which repayment will be triggered at a considerably higher level of income and the less affluent will be altogether exempt from fees – which is a more progressive deal than students would have received from a purely Conservative government. The sound, fury and broken glass of the marches tend to distract from the fact that the students' union does not argue that its members should get their degrees free. The NUS favours a graduate tax, which is also a levy on students. All these points can be and are made by Mr Clegg, but they are drowned out by the howl-around of the protesters, the angry cry that the Lib Dems betrayed an election pledge – and so they did.

The Lib Dems have made a painful position even worse by writhing in public about how they will vote. For several days, senior Lib Dems suggested that their ministers might adopt the farcical position of abstaining on the legislation, a stance regarded as absurd by many of the party's own strategists. The rationale was that this might herd their MPs into the same place. I gather that Simon Hughes, the deputy leader, was especially vocal behind the scenes in arguing that trying to get everyone to agree to abstain was the best way to contain the Lib Dems' internal divisions and make the party feel a bit better about itself. Abstention is a theoretical option provided by the coalition agreement.

At the time they struck their deal with the Tories, the Lib Dem negotiators thought they had got themselves a "get out of jail free" card. But it was pretty much bound to become an unsustainable position in government and it became completely unfeasible from the moment that Vince Cable was appointed business secretary and the cabinet minister responsible for higher education.

He could have sub-contracted tuition fees to his Tory deputy, David Willetts. Dr Cable did not do that because he knew it would make him look pathetic. He and Mr Clegg also reasoned – correctly – that they would get a more progressive policy by engaging with the issue rather than trying to wash their hands of it.

Abstaining would also run completely counter to Mr Clegg's strategic approach to coalition, which is not for the Lib Dems to pick and choose between those policies they like and those they find difficult, but to embrace all the government's programme in the hope of getting later credit from the voters for showing that coalition government can be strong and decisive.

Lib Dem ministers are not going to gain the respect of anyone if they abstain on tuition fees. For the students who feel betrayed, it does not make it any better for the sell-out to be accompanied by a cop-out. In fact, were I one of those students, I would feel more contempt for an abstaining Lib Dem. For everyone else, their prolonged dither about how to vote on fees conforms to the old caricature of the Lib Dems as a bunch always in search of a fence big enough for all of them to sit on. They have looked like a party that can't even take its own side in an argument.

Senior Lib Dems have surely known all along that it would be ludicrous for Vince Cable to present the legislation to the Commons on Thursday, for Nick Clegg and the rest of the Lib Dem ministers to sit supportively on the frontbench – only for them not to vote. On Friday night, Vince Cable finally said: "Obviously I have a duty as a minister to vote for my own policy – and that is what will happen."

Even this supposed clarification was accompanied by more confusion as party spokesmen continued to insist that he and other ministers might still abstain.

It now looks as though Lib Dems will end up in three places. Those who are members of the government will vote for the legislation. Any minister who can't bear to do so will presumably have to resign or concoct a very plausible excuse for being absent. Some backbenchers will abstain. Other Lib Dem MPs will be in the no lobby with the opposition. That latter group will almost certainly include Mr Clegg's two immediate predecessors as leader, Menzies Campbell and Charles Kennedy.

Such a three-way split will embarrass the Lib Dems, but it is not the end of the world. There were rebellions aplenty by Labour MPs when their party was in power. There have already been quite a few, little-reported, revolts against the coalition by numerous Conservative MPs. A backbench rebellion does not have to be fatal for Nick Clegg providing his party doesn't go on to make a habit of it.

What this week's vote will crystallise is the irreversible change in the reputation of the Lib Dem leader. The Cleggmania of the election campaign, when he so enjoyed being feted by adulatory mobs, has been replaced by the Clegg-hating crowds who burn him in effigy. He is not the first politician to travel this trajectory. Many party leaders start off loving to be loved and then have to find ways of dealing with being loathed.

Tony Blair once mused: "I began hoping to please all of the people all of the time; and ended wondering if I was pleasing any of the people any of the time." He reconciled himself to that change by deciding it was ultimately better to be respected than to be liked. Nick Clegg's hope for the longer term is that he will eventually earn credit with the country at large for being prepared to tough out unpopularity for the sake of making choices that he believed to be right.

The difference is that it took about six years for Tony Blair to journey from wanting love to seeking respect. Nick Clegg has accelerated down that road in just six months. No wonder many in his party are feeling car sick.