Dozens of British lawmakers said they will vote to authorise the start of European Union exit talks - signalling likely victory for the government on the vote it had fought in court to avoid.
The House of Commons began a two-day debate on a bill that lets Prime Minister Theresa May trigger two years of divorce negotiations, as the government races to meet a self-imposed March 31 deadline to begin the process.
The government was forced to introduce legislation after a Supreme Court ruling last week torpedoed May's effort to start the process of leaving the 28-nation bloc without a parliamentary vote.
The government argues that British voters decided to leave the EU in a June 23 referendum, and no further authorisation is needed.
Brexit Secretary David Davis said legislators had to answer a simple question: "Do we trust the people or not?"
"It's not a bill about whether the UK should leave the union or indeed about how it should do so," he said.
"It is simply about Parliament empowering the government to implement a decision already made - a point of no return already passed."
Scores of lawmakers stood to speak in a debate that began at lunchtime and looked set to stretch on until midnight.
A majority from both the governing Conservatives and the opposition said they would respect the voters' decision and back the bill.
Anti-EU legislators did so with enthusiasm. Pro-Brexit Conservative Bill Cash said the vote to leave the EU was a "peaceful revolution" on a par with votes for women and the working class.
Fellow Conservative John Redwood said Brexit would transform Britain's legislature from a "puppet Parliament" overshadowed by Brussels, to a Parliament "made great by the people.
But many pro-EU legislators agreed to back the bill with reservations, expressing fears that Britain will be poorer and more isolated outside the bloc's single market of half a billion people.
"You can't go back on your word because you don't agree with the result," said pro-EU Conservative Anna Soubry.
"But I want to say this: I believe history will not be kind to this Parliament nor indeed the government I was so proud to serve in."
The main opposition Labour Party said it would try to amend the bill to give lawmakers final approval of a settlement with the EU, but not block it.