British Prime Minister Theresa May on Saturday told the "plotters" planning to overthrow her that their alternative Brexit plans would not make all the problems disappear.

May is fighting to salvage her draft Brexit deal and her job after a tumultuous week in which four ministers resigned, MPs slammed the proposal and members of her own party tried to oust her.

But she insisted there was no better option on the table and any alternative plans would still not conjure up a solution to keeping open the border with the Irish Republic.

"People say if you could only just do something slightly different, have a Norway model or a Canada model, this backstop issue would go away. It would not. That issue is still going to be there," she told the Daily Mail newspaper.

"It's not everybody's ideal deal. You were never going to get that."

"The job of prime minister is to make tough decisions which are not always black or white. I have to find a way through, what best suits everybody's needs."

May received the backing on Friday of Michael Gove and Liam Fox, the last remaining pro-Brexit heavyweights in her cabinet.

But the pair and three other cabinet Eurosceptics, Andrea Leadsom, Penny Mordaunt and Chris Grayling, were meeting over the weekend to try and force May to change her Brexit plans, the BBC and The Daily Telegraph reported.

Leadsom said there was still "more to be done" on the deal.

She told Sky News television she was "absolutely determined to support the PM in getting the best possible deal for the UK as we leave the EU."

"There is still more to be done and we do still have more time before the EU Council at the end of the month so I'm absolutely committed to getting the Brexit that 17.4 million people voted for," she added.

'Unprecedented onslaught'

May could yet face a vote of no confidence from her own MPs.

At least 48 Conservative MPs are required to submit letters of no confidence in the party leader to trigger a vote, and 23 have publicly confirmed they had done so.

Scottish secretary David Mundell pledged his support for May amid what he called the "unprecedented onslaught."

Mundell said he has reservations about the draft deal but other alternatives were "even more unpalatable."

"She is tackling an issue of epic proportions, on which she can never please everyone, and she is doing her very best to find a way through," he said.

"If it comes to a confidence vote, she will have mine."

The 585-page draft deal aims to ensure a smooth divorce from the EU after more than four decades of membership and outlines a transition period for both sides.

But MPs told May on Thursday that there was no chance of it securing majority support in parliament.

Eurosceptic MPs fear the deal would keep Britain shackled to Brussels long after Brexit on March 29, 2019.

EU supporters say the draft deal would leave the UK on worse terms than it has inside the bloc, calling for a second Brexit referendum to break the logjam.

(Top image: British Prime Minister Theresa May speaks during a conference, London, UK, November 15, 2018. /VCG Photo)

(Source: AFP)