Greater Manchester leaders have been given a deadline of midday to reach a deal with the government over moving to tier three Covid restrictions.
If a deal is not reached, Communities Secretary Robert Jenrick said the PM would decide on the next steps.
In this situation, the BBC's Laura Kuenssberg said the "implication" was the top tier of rules would be imposed.
Greater Manchester Mayor Andy Burnham said the region was seeking a "fair figure" of support from the government.
Mr Burnham told BBC Radio 4's Today programme he would be meeting with local leaders this morning and would advise them to set out the request in a letter to the government.
The government and local leaders - including mayors and MPs - have been embroiled in 10 days of talks over moving Greater Manchester's 2.8m population from tier two to the highest restrictions.
Greater Manchester has been under local restrictions since July.
The "very high" alert level - also known as tier three - would mean closing pubs and bars which do not serve meals, and additional restrictions on households mixing.
Mr Jenrick said local leaders had been "so far unwilling to take the action that is required to get this situation under control".
It come as the number of weekly registered coronavirus deaths in England and Wales rose by 438 and increased by a third in the space of seven days, according to official figures from the Office for National Statistics.
Speaking to Today, Mr Burnham described the government's "late-night ultimatum briefed to the media" as a "slightly provocative move", but he said he was going to "try and find a way forward".
He said local leaders had never been given a figure for additional financial support in return for further restrictions.
As well as setting out what a "fair figure" of support was, Mr Burnham said he wanted "full flexibility" to support people who will be affected by restrictions.
He said: "I think it is fair to recognise that if you put a place under restrictions for as long as we've been under restrictions it grinds people down. It pushes businesses closer to the brink."
Mr Burnham has previously called for the government to reintroduce the 80% furlough scheme used during the UK's first lockdown, instead of the new Job Support Scheme which covers 67% of the wages (covered by employers and the government) of people affected by tier three closures.
Business minister Nadhim Zahawi told Today £22m had been offered to Greater Manchester - equivalent to £8 per person - and there would be "additional support commensurate with what we have done in Liverpool City Region and in Lancashire".
Shielding 'part of solution'
Mr Burnham said he would not "break the law" if no agreement was reached between both sides and the government imposed tier three measures on Greater Manchester.
"It's their prerogative to do what they think is needed," he told BBC Breakfast.
"But I would say to them that I don't think it will help us bring people with what they want to do to control this virus. I think it would be better to come to an agreement."
Mr Burnham also said he thought the shielding of elderly and vulnerable people in Greater Manchester needed to be "looked at seriously" and suggested it was "part of the solution".
Sir Richard Leese, the Labour leader of Manchester City Council, told BBC Newsnight he hoped a deal could still be made, but added: "If government imposes tier three - and I hope that won't happen - we will clearly need to comply with that."
On Monday, Mr Burnham and Sir Richard accused the government of using "selective statistics" on hospital occupancy rates to bolster the case for tougher rules.
On Monday evening, the two sides couldn't even agree on what they actually discussed earlier.
Believe the local leaders and on Monday morning there seemed to be hope in the air. Officials from central government had mooted the possibility of a hardship fund to help support low-paid workers who stand to lose out if businesses close their doors under tighter restrictions.
The message local leaders took from their meeting was that, while the Treasury is adamant they are not going to extend their national furlough scheme - nor increase the level of cash available from its replacement, the Job Support Scheme - Westminster might sign off extra money that could be spent that way, if local politicians saw fit.
There was no concrete agreement on the numbers, but sources in Greater Manchester suggest the cost of supporting those who need the extra help comes in at around £15m a month.
After that call, the consensus among North West leaders was moving in the direction of signing on the dotted line, with another call planned with Communities Secretary Robert Jenrick for the afternoon.
But rather than ushering in a new spirit of co-operation, that meeting went south.
A three-tier system of alerts was announced a week ago in an attempt to control rising coronavirus cases without a UK-wide lockdown.
However, Health Secretary Matt Hancock told the House of Commons on Monday that discussions are planned for South Yorkshire, West Yorkshire, Nottinghamshire, north-east England and Teesside also moving into the top tier.
Speaking ahead of those discussions with government, Nottingham City Council leader David Mellen said he would make clear "that we want a package that properly protects local people, businesses, jobs and education, whether it's for tier two or tier three".
Elsewhere in the UK, in Wales people will be told from Friday to stay at home, while pubs, restaurants and non-essential shops will shut, as part of a "short, sharp" national lockdown until 9 November.
A two-week school closure has begun in Northern Ireland as part of a tightening of restrictions.
In Scotland, the tightest restrictions are in place in the central belt, and there are plans for a three-tier framework of measures, similar to England's.
On Monday, government figures showed the UK recorded a further 18,804 coronavirus cases and 80 deaths.
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