Analysis By Nick Assinder Political correspondent, BBC News website

Tony Blair may have changed his mind over nuclear power during the past three years but many more minds will have to be changed if his vision is ever to become a reality.

Blair will not persuade protesters

The prime minister has little hope of winning over the likes of Greenpeace, Friends of the Earth or the Green Party who are vehemently opposed to nuclear and are pressing the government to invest more in renewable energy.

But powerful opposition is also coming from the Liberal Democrats, whose policy is to oppose nuclear power, specifically on the grounds it would crowd out investment in alternatives.

And many Labour backbenchers remain fundamentally opposed to nuclear energy, with around 60 having signed a Commons motion opposing the move.

And the prime minister is not the only senior Labour figure who once expressed opposition to nuclear power.

When the government published its energy White Paper in 2003, it called for massive reductions in CO2 emissions, a huge boost to renewables like solar, wind and tidal power, and energy efficiency programmes.

Death knell

But it also ruled out building new nuclear power stations to replace existing ones coming to the end of their lives, stating nuclear was an "unattractive option".

It did leave the door ajar for future atomic plants, but the then Trade Secretary Patricia Hewitt warned any new nuclear investment would undermine the drive for energy efficiency and renewables.

Nuclear was seen as unattractive option

Although she added: "We are not absolutely ruling out new nuclear build forever".

At the time, Friends of the Earth welcomed the policy as "the death knell for nuclear power in Britain".

A group of ministers, including Foreign Secretary Margaret Beckett and Northern Ireland Secretary Peter Hain, are said to retain doubts over the policy although, crucially, Chancellor Gordon Brown supports the prime minister's view.

Meanwhile former environment ministers Michael Meacher and Elliot Morley are leading Labour opposition from the backbenches.

The Tories are so far hedging their bets, claiming only that, while there "might be some more nuclear" in future, it should be seen as a last resort.

Hard message

And they greeted the review by claiming the government had failed to show exactly how it would go about building new stations, and how many.

But, perhaps most dangerous of all, if recent polls are correct there is little support amongst voters for a new generation of nuclear power stations.

Government wants big boost to renewables

The prime minister answers all this by saying things have changed since 2003 and led him to reassess the position.

While he is still giving a big push to renewables and efficiency, he no longer sees an alternative to including nuclear in the mix because, by 2020, Britain will have gone from being self-sufficient in energy to 90% dependent on imports.

The latest buzz phrase from Downing Street is: "wishful thinking won't keep the lights on".

That is the hard message the prime minister - and, presumably, Gordon Brown - now have to sell to the country.

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