The two leaders sat down for a working lunch, during which May "outlined the steps the government is taking to bring the Brexit process to a successful conclusion", according to a Downing Street spokesperson.
Since then May has held talks with the Labour party in a bid to find a compromise solution that can win a majority in parliament.
Britain's Parliament yesterday passed an "insurance policy" law created to ensure the country does not leave the European Union without a divorce deal.
Mr Tusk's letter came after the PM arrived in Paris for talks with Mr Macron, who in recent days has warned that an extension to the Article 50 withdrawal process is not guaranteed.
These would limit the power of Britain's commissioner in the European Commission, the EU's executive arm, and the role of the British prime minister at meetings of EU leaders, the aide said.
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.
Allison Mack pleads guilty in group's sex cult case
She has pleaded not guilty and was released on a $100 million bond, according to the Associated Press . Prosecutors accused Mack of helping Raniere recruit women to a secret sub-society within the group.
EU Council President Donald Tusk on Tuesday urged the bloc's leaders to allow Britain to delay Brexit for up to a year as London and Brussels scramble to avoid a chaotic "no deal" exit on Friday.
Labour business spokeswoman Rebecca Long-Bailey said there had not been "any fundamental shift. but we're hopeful that progress will be made".
European Union leaders, tired 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.
But British Prime Minister Theresa May still has a rough day ahead of her as she heads to an emergency summit in Brussels on Wednesday to plead for a new Brexit extension - for the second time in three weeks.
Such an extension would mean the United Kingdom had to take part in European parliamentary elections, a prospect anathema to hardline Brexiteer Tories.
Earlier on Tuesday, an aide to French President Emmanuel Macron said France was not opposed to extending the Brexit deadline but would push for strict conditions to be attached, adding that a year would be "too long".
Nipsey Hussle's Memorial To Be Held At The Staples Center
Kodak Black is apologizing after causing controversy for his comments about the late Nipsey Hussle's girlfriend, Lauren London . I'll try to be like the friend if you need to holla or a shoulder to lean on. "Man, listen.
The country could still crash out of the European Union without a deal if the bloc's leaders refuse to grant a delay.
With further talks scheduled on Tuesday between his team and government ministers, Corbyn said that "the prime minister has not yet moved off her red lines so we can reach a compromise".
A party spokeswoman said: "We had further detailed and wide-ranging talks with Cabinet ministers and officials today".
Conservative MP Mark Francois on Monday called for a vote on May's leadership, despite party rules dictating that a confidence vote can not be held until December - a year after a previous attempt to remove her failed.
MPs will be allowed to vote on this and make their own suggestions as to the length of the delay.
Nipsey Hussle Murder Suspect Eric Holder Charged in Rapper's Death
After a widely publicized manhunt, he was arrested on Tuesday in the city of Bellflower, in Los Angeles County. Holder has not entered a plea yet and it is unclear if he has an attorney, according to the Associated Press .