In sharp contrast to rumours she would be gone by Christmas, Theresa May is being urged to stay on as leader at least until 2021 so as not to endanger Brexit talks on trade.

Even after losing a bruising Commons vote in which rebels from her party backed a final deal vote by parliament on Britain's Brexit deal, the prime minister can rely on fears by senior Tories that another party election could hurt EU trade talks which will probably continue until after March 2019.

A cabinet minister told the Times: "She is not one to up sticks and leave. I'm confident that she will go on long beyond when many people expect. There is no clean and simple moment when she will or can leave. I think the leadership contest will be pushed back and back."

Another senior minister told the paper that the prime minister "will have to stay on indefinitely, not least because the government will fall if she goes."

Key Brexit-backing Tory MP Jacob Rees-Mogg MP said: "She has to stay until Brexit is completed because obviously it would become the most heated part of any leadership contest."

The chief EU Brexit negotiator, Jean Michel Barnier, told Prospect magazine that the UK would not be able to take the best aspects of trade deals the EU has with Canada and Norway, saying: "they have to realise there won't be any cherry picking", although this has been dismissed by some as a negotiating tactic in its own right.

Theresa May
British Prime Minister Theresa May arrives for the European Union leaders summit at the European Council on December 14, 2017 in Brussels Dan Kitwood/Getty Images

The prime minister will tell the Commons on Monday (18 December) that the UK can negotiate and sign new trade deals during the transition period until 2021.

She is expected to say: "We would propose that our access to one another's markets would continue as now, while we prepare and implement the new processes and new systems that will underpin our future partnership.

"During this period we intend to register new arrivals from the EU as preparation for our future immigration system," the Telegraph reported.

Meanwhile the Guardian reported that Tory rebels want the prime minister to form a cross-party alliance with support from Labour to ensure a softer Brexit.

One Tory rebel who voted against the government for the seventh amendment to the EU Withdrawal Bill, told the paper: "At the moment, the Labour party is terribly divided and therefore there are quite a large body of independent-minded Labour MPs who would be willing to respond positively to a request to provide support to a government that is seen to be doing the right thing."