British lawmakers should back Prime Minister Theresa May in a vote in parliament later on Thursday, her spokesman said, to send a clear message to Brussels about what changes the country wants to its Brexit deal.

“It is important that MPs (members of parliament) support the prime minister today in order to send another clear message to Brussels on the need to address parliament’s concerns about the backstop so we can leave on time with a deal on March 29,” the spokesman said.

The spokesman added that the option of leaving the European Union without a deal remained on the table.