The Rev Leslie Griffiths, in his first presidential address to 700 delegates at the annual conference, held in Leeds, attacked the Government's record and warned that 15 years was too long for one party to hold power.
Dr Griffiths, told the conference, which represents more than a million worshippers in Britain, that he was hoping for change soon 'for the good of the country and the health of our civil society'. He told delegates: 'No government, of this or any other hue, can be allowed to hurt people or drive them to the margins of society.'
Dr Griffiths criticised the Government's record on unemployment, homelessness and student impoverishment and attacked the prevailing 'bewilderment' within the National Health Service.
He said that when church leaders put their heads above the parapet the predictable result was to be told to keep their noses out of politics and stick to spiritual matters.
'But what could be more spiritual than the way measures and laws passed in parliament affect the lives of ordinary people, defining their horizons, shaping their future, raising or crushing their hopes?' he said. Dr Griffiths added that it was 'the spiritual duty of the church to stand by those who suffer'.
The 51-years-old Welshman went on: 'The activity of the politicians directly affects the state of the nation, its soul, its well-being, its physical, moral, and spiritual health . . . Which is why church leaders must, as a matter of duty, monitor what politicians do with great care . . . It is a very dangerous thing to leave politics to politicians,' he added.
'In my view, 15 years is too long for one single party to hold power. So many people are longing for a change . . . Our political system is built on the assumption that power will be held from time to time by different parties. Surely this must happen, and soon.'
In a forthright speech, Dr Griffiths also called for electoral reform and espoused 'some form of proportional representation, so that we never again have the kind of situation we have at the moment'. He said that 'an over-long period where one party holds power weakens every part of the body politic'.
Yesterday's session took place 250 years to the day after the opening of the first conference which John Wesley, the founder of Methodism, convened in London on 25 June 1744.
Dr Griffiths' attack mirrored similar criticisms made five years ago by the then president, the Rev John Vincent.
In an open letter to Mrs Thatcher, which was delivered to Downing Street after the Prime Minister - the daughter of a Methodist lay preacher - refused to see church representatives, Dr Vincent said that Conservative policies had created an underclass of deprived people.
The Bishop of Durham branded Prime Minister John Major's stance on beggars as 'inhuman'.
The bishop, Dr David Jenkins, who retires next Sunday after 10 years in office, said government moves to rid the nation's streets of beggars were misguided.
In an interview broadcast on Radio 5 Live's Alistair Stewart's Sunday, he condemned Mr Major's statements on beggars.
He said: 'It sounded like an inhuman thing to say, you know 'these beings are causing us trouble, sweep them away'.
'That is wrong because all human beings are human beings and shouldn't be swept away. It is a pity that it is put in the context of thinking you can just sweep them away as if they are not also part of us and also symptoms of the society in which we've got the problems.'
The bishop also doubted whether a future Labour government would tackle society's problems.
He said: 'I am not at all sure how far the Labour Party has really got to grips with the need for serious alternative thinking about how . . . we get round to practical loving of our neighbour, which was the inspiration of socialism in the old days.
'I think if, as I hope, Labour or a coalition come into power then they've got a hell of a lot of thinking to do.'
Churchgoers are being urged to make today a day of rest for their cars to highlight the environmental damage caused by air pollution.