"Please, do not waste this time", European Council President Donald Tusk pleaded.
The further delay comes after an initial extension pushed Brexit back from March 29 to April 12.
Tory MP Conor Burns, an ally of Boris Johnson, said the talks with Labour amounted to "two Remainers debating how to compromise on something that really isn't even Brexit", adding: "This has moved beyond embarrassing to humiliating".
German Chancellor Angela Merkel has made it clear repeatedly that she wants an orderly British departure and is ready to exercise her patience to achieve that.
In the end, the European Union leaders hammered out a compromise - giving May more time than Macron wanted to give her to steer a departure deal through her country's bitterly divided parliament, while simultaneously shaving months off Tusk's suggestion.
Britain was due to have left the EU before European elections in late May.
"Even if Annunziata went off and became a communist she would still remain my sister".
If May fails to win over lawmakers on the treaty or fails to hold an election, Britain will leave with no deal on June 1. That's anathema to a lot May's Conservative Party, who say that it would not render Britain liberated to strike its trade deals across the globe.
Unable to convince enough of her Conservatives and their Northern Irish allies to back the deal, May last week chose to try finding a compromise with the main opposition Labour Party.
May had previously ruled this out because it prevents Britain from striking lucrative independent trade agreements with giants such as China and the United States.
That said, it is highly likely these cross-party talks will simply fail. Still, the negotiations are set to continue.
The Daily Telegraph reported earlier this week that May was considering offering lawmakers a vote on whether to hold a confirmatory public vote on her Brexit deal in a bid to break the deadlock in talks with the opposition Labour Party.
The blueprint hashed out during six hours of talks in Brussels allows the U.K.to stay in the bloc until October 31 to provide more time for the British government to get the divorce terms ratified in Parliament. But it could also blast open rifts within both the Conservative and Labour parties. Government ministers that are pro-Brexit could resign, and stress would rise on May to quit.
"To Theresa May to start talks with someone like Jeremy Corbyn is not in any way easy but she is doing this since she is totally and utterly determined to deliver Brexit", Hunt said prior to a meeting of European Union foreign affairs ministers.
However, her path toward actually taking Britain out of the European Union remains unclear.
She's brushed off yet more pressure to step down - as one senior backbencher accused her of "abject surrender" to the EU.
Labour is pushing for a general election that could bring it to power for the first time since 2010.
As it stands, the next Brexit cliff-edge is October 31. "I think politics is broken".
Votes in the fractious House of Commons have shown that none of the alternatives to May's agreement - such as leaving with no deal, a referendum or a much closer post-Brexit economic relationship - can yet muster a majority. "Until the end of this period, the United Kingdom will also have the possibility to revoke Article 50 and cancel Brexit altogether". If that happens the only way to stop Britain crashing out would be for the Government to choose the "nuclear option" and revoke the decision to leave. He said it was not on the minds of the European Union leaders.