A re-elected Labour government would put nuclear power back on the agenda in an effort to meet targets on climate change, government sources have said.
A public debate on nuclear power could be opened
The sources told BBC News Tony Blair wanted a national debate on the issue.
He would raise the issue when ministers responded to a climate change policy review in June or July, they said.
The Tories say there should be new nuclear stations provided they meet cost and waste concerns but the Lib Dems oppose the idea.
Mr Blair has said his policy has not changed since the energy White Paper two years ago, which left nuclear power on the back burner.
But a senior source told BBC News Mr Blair would raise the issue in June or July, when the government has to respond to its climate change policy review.
The government says the UK is on course to meet the Kyoto targets on climate change but has admitted it is slipping behind its own tougher targets.
BBC News correspondent Roger Harrabin said the review would not mean a "shoo-in" for nuclear power, but will open a national debate on the topic.
He said the public and cabinet ministers would have to look at whether the threat of climate change was so pressing that the problems of nuclear waste and cost would outweigh the risks.
Last week, Environment Secretary Margaret Beckett said the White Paper on the issue two years ago had said closing down nuclear power was an option.
"But we also said that there is a huge amount we need to do [to combat climate change], and between 2010 and 2020 we can probably do about at least half of what we need to through energy efficiency and renewable energy," she said.
She added that no company was asking the government to let it build a new nuclear power station.
"In our energy White Paper we said explicitly that if people began to feel that we would have to go towards nuclear power, there would be a further examination then, and a further White Paper," she added.
Conservative shadow environment secretary Tim Yeo said he found it hard to see how the problem of carbon emissions could be tackled if existing nuclear power stations were not replaced.
A decision was needed within a year of the election, he said.
"We believe nuclear power can play a role in addressing this problem providing it is cost-effective and provided it can satisfy people's concern about waste disposal," he explained.
Lib Dem environment spokesman Norman Baker said relying on nuclear power to tackle climate change was "like jumping from the frying pan to the fire".
"Nuclear power may not have the problems associated with carbon emissions, but it does produce tonnes of radioactive waste that costs billions to store and will pose a risk to humans for thousands of years after disposal," he said.
For the Green Party, Darren Johnson said nuclear reactors had an operational life of between 30 and 40 years but created waste that lasted "thousands".
"It is barking mad to consider nuclear power as part of a sustainable energy policy," he said.