The UK government is preparing to reject any call from Scotland's First Minister Nicola Sturgeon for the power to hold another independence referendum, sources have told the BBC.
Ms Sturgeon has said she will reveal her next steps on independence soon.
There is an expectation at Westminster that she will call for the power to hold another referendum in the coming weeks.
But cabinet sources have dismissed the prospect.
Senior figures in the SNP say they may use a further election to try to force the issue.
Downing Street last rejected calls for another independence referendum in 2016 - when Theresa May said: "Now is the not the time".
What's going on?
The Scottish government has said it will announce its views on the possibility of another independence referendum soon.
Ms Sturgeon and her team are keeping their cards close to their chests.
But the issue is being talked about in the corridors of power at Westminster.
What's the UK government saying?
The working assumption in Whitehall is that Nicola Sturgeon will call for a section 30 order - which transfers the power to hold another referendum to the Scottish Parliament.
One source close to the prime minister said: "The PM is in no mood to acquiesce to another referendum now - she would flat out say no."
Another told me: "There is no answer to this, other than now is not the time."
A cabinet minister said: "I couldn't imagine any circumstances in which she is going to say 'yes'."
And another member of the government added: "The PM will knock it straight back."
The argument they make is twofold.
Firstly they believe, based on internal polling, that opposition to holding another referendum is hardening.
Secondly, they say with so much attention on Brexit, an independence debate would be a distraction.
One minister said: "Once you've hit the iceberg, you're all on it together".
What are the SNP saying?
Senior figures say they expect Nicola Sturgeon to ask for the power to hold another referendum when she makes a keynote speech in the next few weeks.
They point out the SNP's manifesto for the last Scottish election said she had the right to do exactly that, if Scotland voted against Brexit but the UK as a whole decided to leave.
But there is acknowledgement that the answer from Downing Street will be 'no'.
So the party is war gaming what to do next - and how to try to force the issue.
In the words of a senior SNP figure at Westminster: "We have a mandate - we have to find ways of that being reinforced.
"The party, the wider Yes (to independence) movement will have to demonstrate there is public support".
That could take different forms.
"We will use whatever opportunities there are in front of us to reinforce the mandate we have".
But some think another election would be helpful to persuade the UK government that it can't ignore their call.
"It is pretty obvious what we'll campaign on", a source said, adding that the party should have been stronger on the independence issue in 2017 because it would have motivated the 45% of Scots who backed independence in 2014.
That sets up the prospect of the Scottish Parliament election in 2021 - or even a snap general election - becoming a referendum on a referendum.
Does everyone in the SNP agree?
On the principle that the Scottish Parliament should have the choice of when another referendum should be - yes.
But there is considerable debate in the party on when another vote should happen.
Several SNP MPs have said they want to fire the starting gun as soon as possible, arguing Brexit is a mess and Scotland should be able to change path.
There is even some disquiet about Nicola Sturgeon's approach. One MP said the first minister was "asleep at the wheel".
But others are considerably more cautious. Another senior MP said there shouldn't be another referendum until at least 2025 - adding: "We're just not ready."
There is an interesting sub-plot to this. Some Scottish Tories are urging the prime minister, if she ever does say yes to another referendum, to keep hold of all the cards. One MP said control over the date, question and franchise should be set by London.
What happens if Brexit goes badly?
There are fears in the UK government that a particularly chaotic Brexit could threaten the future of the UK.
We've already reported that some ministers are concerned about the impact of a no-deal Brexit on the union - perhaps leading to a border poll in Northern Ireland.
Some also think it could make Scottish independence more realistic.
One source warned Conservative colleagues against creating "an environment of chaos, disruption and uncertainty."
They added on Scottish independence: "The dial hasn't been moved - the dial could be moved."