Theresa May will make a third attempt to get her EU withdrawal deal through Parliament in the next week, BBC reports.
She told MPs that if her deal fails again to get their backing, a lengthy delay to Brexit may be needed.
The prime minister's warning comes ahead of a Commons vote later on whether to ask the EU for permission to delay Brexit beyond 29 March.
MPs voted on Wednesday evening to reject a no-deal Brexit under any circumstances.
No date has yet been set for the third so-called "meaningful vote".