It could be a day of reckoning for Theresa May.
Her long awaited Brexit deal last week was met with ministerial resignations and open talk of ousting her as leader.
But Britain's Prime Minister has vowed to keep fighting.
In a speech on Monday (November 19) she sought to defend her plan and win support from business leaders.
(SOUNDBITE) (English) BRITISH PRIME MINISTER, THERESA MAY, SAYING:
"Europe will always be our most proximate goods market and ensuring we have free flowing borders is crucial.''
May could face a vote of no confidence by her Conservative lawmakers.
(SOUNDBITE) (English) EUROSCEPTIC LAWMAKER JACOB REES-MOGG SAYING:
''This is not Brexit. This is a failure of government policy. It needs to be rejected.''
One will be triggered if 48 of them write letters requesting it.
The Sun newsapaper says the number stood at 42 on Monday morning.
One of the resignations was Britain's Brexit minister himself - key to shepherding the new deal through.
(SOUNDBITE) (English) BRITAIN'S FORMER BREXIT MINISTER, DOMINIC RAAB, SAYING:
"I was being asked to go and sign on a dotted line with Michel Barnier and I just didn't feel in good conscious to do that."
He's already been replaced by a little-known junior minister in preparation for the week ahead.
More than two years after the United Kingdom voted to leave the EU, it is still unclear how, on what terms, or even if it will leave as planned.
(SOUNDBITE) (English) THERESA MAY SAYING:
''Am I going to see this through? Yes.''
That clarity could come this week.
If it does, all eyes will be on a Sunday (November 18) EU summit, where leaders are to endorse and formalize the deal.