Brighton, United Kingdom - Calls for a second referendum on Brexit are mounting as Britain approaches the last six months before leaving the EU -- but the sands of time could be running out for diehard Remainers.
London Mayor Sadiq Khan this week became the latest big name to call for a vote, joining former prime ministers Tony Blair and John Major and celebrities like football star Gary Lineker.
The Liberal Democrats, the only major political party advocating a vote, will push their message again at a conference on Tuesday.
At the meeting in Brighton, party leader Vince Cable will urge Prime Minister Theresa May to "lead her party and the country by opening her mind to a people's vote on the final deal".
The government is opposed, while the main opposition Labour Party is not supporting the calls but also not ruling out the prospect.
Supporters of a second referendum are also divided over what the actual question might be, including whether it should include a question on staying in the EU.
"What would a second referendum be about? That's not clear at all," said London School of Economics professor Sara Hobolt.
- Referendum 'unlikely' -
Time is running down, as Britain is set to leave the European Union on March 29, 2019.
In the 2016 referendum, 52 percent voted to leave and 48 percent wanted to stay.
Hobolt said polls indicate those proportions have reversed, with 52 percent who would now back staying in the bloc.
She also pointed to "a marked increase in people's support for a second referendum", pointing to a YouGov poll in July in which 42 percent of Britons favoured a referendum on the terms of the Brexit deal -- against 40 percent who were opposed.
But Hobolt doubted whether a new vote could take place without the support of either of the main parties.
May said Monday she thinks the only alternative to her blueprint to stay close to the EU on trade would be no deal at all.
But she has said a second referendum on any options would be a "gross betrayal" of British democracy.
- Delay Brexit? -
Bookmakers reckon the odds of a second referendum are around one in four.
Some commentators say that technically it may already be too late.
They say there would not be time to hold a referendum and for the British and European parliaments to ratify any deal by Britain's departure date.
University College London's Constitution Unit calculated in a report that the earliest possible date for a referendum would be March 28 -- a day before exit day -- and said the only alternative would be to delay Brexit.
"To hold a referendum, Article 50 would almost certainly need to be extended and exit day postponed," the report said.
- 'Let the people decide' -
The main force calling for a second referendum is the cross-party People's Vote campaign -- the successor of the official Remain campaign from the 2016 referendum.
Launched in April this year, it pumps out several press releases every day, each explaining why the latest twist in the Brexit process necessitates a second referendum.
Five months on, though the campaign has gained traction, a referendum -- and what it would ask -- seem no closer.
The campaign garnered momentum in July when Conservative former cabinet minister Justine Greening broke ranks, saying a three-option referendum was the only viable way to break the parliamentary deadlock.
The three choices she proposed were for Britons to be asked whether they approved of any deal negotiated by the government, whether they supported leaving with no deal or whether they preferred remaining in the EU.
And prominent anti-Brexit campaigner Gina Miller turned up the temperature on Monday, telling the Liberal Democrat conference in Brighton: "Make no mistake: time is running out.
"It's time for politicians to do the morally and democratically right thing -- to let the people decide their own future on the facts -- before it is too late."
By Robin Millard