Nick Raynsford, minister for London, said: 'It will be the largest personal mandate of any political position in the country with a five million electorate and an immediate responsibility for a budget of£3.3bn a year.'
He added: 'It's a big, big job for someone who has really got an appetite to tackle pretty difficult problems and an ability to solve them - a really major constitutional change.'
The Greater London Authority Bill yesterday began the committee stage in the commons.
The new boundaries proposed by the Local Government Commission will have electorates of about 400,000 and would be in place by the elections in May next year.
The deadline for nominations was set at February 28 and final candidates would be announced in September.
Mr Raynsford hailed the new assembly as the 'smallest and most cost-effective of any city-wide administration in the world'.
The government has proposed a number of amendments to the bill, including a quarantee that funds raised from traffic charges would be spent on improving transport links for at least ten years.