Boris Johnson has been warned that a planned coal mine in Cumbria is damaging his reputation, at a time he wants to lead the world on climate change.
Supporters say the mine will create hundreds of jobs and produce coal needed for UK steel, but government climate advisers say it is bad for the planet.
What is the case for the mine?
Cumbria County Council had originally backed plans for the new mine, but is now reviewing its decision.
The area, in north-west England, is dominated by the giant Sellafield nuclear plant, and West Cumbria Mining promises hundreds of well-paid jobs.
Coal from the mine could support steel-making in the UK and using British coal would save the carbon emitted by shipping it from Australia or North America.
Why do environmentalists oppose it?
The UK, along with other countries, has agreed to drastically cut carbon. The government's climate advisory Climate Change Committee also worries that allowing this mine to open would cause more problems.
It says to meet its carbon-cutting timetable, steel firms must stop burning coal by 2035 - unless they fit expensive technology to capture the emissions and bury them underground.
The committee points out that 85% of the Cumbrian coal will be exported anyway, and every extra tonne of coal on the world market will tend to drive down the cost and drive up emissions.
In November the UK is holding a mission-critical climate summit and some members fear the mine row will undermine the prime minister's leadership.
Does the UK steel industry need Cumbrian coal?
This is a controversial issue and few in the industry are prepared to speak publicly.
One said a supply of Cumbrian coal would allow his firm to save some cash by making more flexible orders. But he, and other industry figures I approached, said there were reliable supplies of suitable coal on the world market, and that Cumbrian coal was not essential for their business.
They also think investors will want to put money into clean steel production in future.
What are the alternatives to coal for the steel industry?
Steel-making is a problem area for climate change, but firms are developing technologies like electric arc furnaces - which melt down recycled steel - and hydrogen, which can be used to make steel for cars.
Supporters of the mine say coal will definitely be needed for steel after the climate committee's 2035 deadline.
But the European steel industry, Eurofer, told me clean steel technologies might be available by then - so long as governments support research and development, and block unfair competition from dirty steel imports.
What about the jobs?
The firm says the mine will create 500 jobs, but sceptics think that's exaggerated. Unemployment in the area is less than the national average, but over 40 Conservative MPs have signed a letter in support of the mine.
An independent report next month will outline opportunities for Cumbrian clean jobs in areas like renewables, recycling and public transport. But these may look uncertain compared with hundreds of jobs in a mine.
Are other countries facing the same dilemmas?
Every nation accepts that carbon emissions should be cut immediately. But countries with valuable fossil fuel reserves don't want to abandon them and the jobs they sustain - even if renewables technologies may be creating more jobs elsewhere.
This applies to China and the US - where President Biden has not banned fracking. The UK is phasing out coal for electricity from 2024 but ministers suggest there's still a case for producing suitable coal for steel.
The issue is embarrassing for the UK, because it initiated the global "Powering Past Coal" alliance of countries seeking to persuade others to swap jobs in coal for jobs in clean sectors.
So what happens now?
Cumbrian councillors will reconsider the mine application in the next few weeks in the light of the climate change evidence that wasn't available last time they considered it.
If they kill the project, the prime minister will breathe a sigh of relief because it's out of his hands. If they grant approval again it will be up to Communities Secretary Robert Jenrick to decide again whether to over-rule it.
Under planning law he's supposed to make that decision without referring to his colleagues. But it's barely conceivable that Boris Johnson, with his reputation on the line, won't find a way of pointing him in the right direction - whichever way he thinks that is.
Follow Roger on Twitter @rharrabin