Every party leader will go into this week’s local elections with a sense of trepidation but none more so than Gordon Brown. After he funked a general election in the autumn this is the first opportunity voters have to give their verdict on his government. In 155 councils in England and Wales, and in Greater London, that verdict will set the political tone for the run-up to the next general election.

The omens for Mr Brown are not good. His mis-handling of the abolition of the 10p tax rate, culminating in last week’s embarrassing climb-down, was a political crisis of his own making. Labour has plunged in the polls to its lowest level since Michael Foot led the party into the wilderness. To add to his troubles, Mr Brown has sleep-walked into a dispute that has shut down more than a third of Britain’s North Sea oil output and led to fuel shortages and panic buying. A similar episode gave Tony Blair a political scare eight years ago. He recovered. Mr Brown may not.

According to psephologists Colin Rallings and Michael Thrasher of Plymouth University’s Elections Centre, the situation may be even worse than the polls suggest. Their Sunday Times by-election model shows Labour support on just 25% and on course for the party’s worst local election results for 40 years when Harold Wilson caught the full vent of anger over the November 1967 devaluation. Two years after the 1968 locals, he lost the general election. Today, voters are again experiencing the cold wind of austerity and a weakening pound.

The intricacies of local elections are often lost on ordinary voters. Labour ministers will claim the loss of a seventh of their councillors this week as something of a victory given the circumstances. That is why one local contest takes on national importance. Ken versus Boris is the big one. If Ken Livingstone holds on to power in the London mayoral election, Labour will claim that it can still win when it counts.

Does Mr Livingstone deserve a third term? Given his “Red Ken” reputation, his record has been better than might have been expected. He has been a champion of the capital and of the investment banks of the City and Canary Wharf in particular. Originally elected as an independent over Blair’s dead body, he has been welcomed back into the Labour fold and has negotiated good financial deals with the government. He may be wishing that he had stayed independent; polling for this newspaper and others shows that he is comfortably outscoring his party.

But if two terms are long enough for a US president, they are long enough for a London mayor. Mr Livingstone has limped to the end of his second term tired, bereft of new ideas and with corruption allegations swirling around some of his key advisers. Power corrupts and the longer power lasts, the greater the corruption. Mr Livingstone has also shown signs of resorting to the old class warfare, notably with the unnecessary extension of the congestion charge to west London and the proposed £25 daily levy for larger cars.

That leaves Boris Johnson. Many have doubts about whether he is the right man for the job. His campaign has shown that the qualities that have endeared him to voters as a political clown do not translate easily into being a powerful executive mayor. Most Londoners would have difficulty in identifying a Boris policy beyond replacing bendy buses with “21st-century” Routemasters and putting more police on the transport network.

Yet it is time for a change. The Conservatives, if they are ready for government, will ensure that Mayor Johnson is bolstered with enough back-up to make it work. Mr Johnson knows that this is his last shot at demonstrating that he can be a serious politician after many false starts. Above all, a victory for Mr Livingstone would suggest that voters are too forgiving of Labour’s blunders and mismanagement under Mr Brown. They should not be and that message needs to be rammed home this week.