More than a week after Britain was originally supposed to have left the European Union, the weakest British leader in a generation warned that Brexit might never happen as she battles to get a divorce deal ratified by a profoundly divided parliament.
"If the United Kingdom is not capable, nearly three years after the referendum, of coming forward with a solution that is supported by a majority, it will have effectively chosen a no-deal exit on its own", he said.
"No deal in my view would be an an extraordinary failure of politics and we need to ensure that that doesn't happen", he said.
May will seek to reassure European leaders after Jacob Rees-Mogg, a leading Eurosceptic, said that Britain must use its "remaining powers" while it is still in the EU to be "difficult".
Theresa May is heading for top-level Brexit talks in Berlin and Paris as she seeks support for another extension.
British Prime Minister Theresa May toured Berlin and Paris on Tuesday to plead for an extension to the deadline for Brexit, which looked increasingly likely to be approved by European Union leaders at a crunch meeting in Brussels.More news: Notre Dame’s repeat bid falls short on Ogunbowale’s miss
The paper reported: "Mr Macron is already said to be fed up with European summits devoted to Brexit rather than to his own plans for EU reform".
"Neither side should be allowed to feel humiliated at any stage in this hard process", he added.
"Our objective is an orderly withdrawal - no deal will never by the EU's decision".
Ireland, which has much to lose if its larger neighbour quits the block without a deal, has been most supportive of an extension, but Foreign Minister Simon Coveney, also insisted on the need for conditions.
European Union leaders, worn out by the three-year Brexit crisis, have repeatedly refused to renegotiate the Withdrawal Agreement May agreed in November, though on Tuesday there was speculation in London that Merkel might be open to doing just that.
Mrs May and Mr Macron also discussed next month's European Parliamentary elections, with the prime minister saying the government was "working very hard" to avoid the need for the United Kingdom to take part as it is supposed to if it is still a member of the EU on 23 May.More news: Massive python found in South Florida wildlife preserve
Ahead of Mrs May's meetings with her French and German counterparts, details of the EU's potential demands for another extension to the Article 50 period began to emerge in reports.
Following a meeting of the EU's General Affairs Council in Luxembourg, diplomats said "slightly more than a handful" of member states spoke in favour of delaying Article 50 until 30 June but the majority were in favour of a longer extension.
On Monday night, MPs and peers backed a new law to extend the Brexit process and cross-party talks are expected to continue in the hope of finding a compromise.
Environment Secretary Michael Gove said the talks had been "open and constructive" but the sides differed on a "number of areas".
May has asked the European Union for a Brexit delay to June 30 but the draft left the end-date blank pending a decision by the other 27 national leaders on Wednesday evening in Brussels.
After Tuesday's round of talks, Labour said it had not yet seen a clear shift in May's stance.More news: Meghan Markle and Prince Harry host first guest in new their home
Every British initiative to get a deal has floundered so far.