Britain's upper house has inflicted a new defeat on Prime Minister Theresa May's government, challenging her decision to fix a date next year to leave the European Union.
The House of Lords voted for an amendment to a draft law, removing a proposed fixed time for a Brexit departure of 11pm on March 29 next year.
The government has already set the clock ticking on a two-year exit process that has so far failed to deliver a divorce deal and which was damaged by her gamble on a snap election which cost her party its majority in parliament.
Some lawmakers criticised the government's plan to impose a specific date for Britain leaving the EU, saying it would create significant difficulties if negotiations with Brussels went down to the wire.
"It creates a rod for the UK negotiators' backs, weakens any UK negotiating position, and adds unnecessary pressure to those in the executive trying to deliver Brexit in a coherent measured fashion," said Arthur Wellesley, a Conservative member of the House of Lords, who introduced the amendment.
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"We should give ministers a bit more flexibility to secure and obtain ratification of the best possible deal which will do the least damage to the economy and the national interest."
This is the 12th time in recent weeks that the government has been defeated in the House of Lords on the draft legislation that will formally terminate Britain's EU membership.
Earlier, opposition parties in the Lords and rebels in May's Conservative Party voted in favour of the amendment that means Britain should participate in EU agencies after leaving the bloc next year.
The government has proposed retaining membership of some EU agencies for medicine, chemicals and aviation while leaving others after Brexit.
Britain is likely to leave the EU police agency Europol and lose automatic membership to bodies like the European Maritime Safety Agency and the European Environment Agency.
Agencies that oversee Europe's banks and pharmaceutical sector have announced they will move from London to cities on the continent after Brexit, highlighting potential job losses for Britain's economy from leaving the EU.
