The UK Prime Minister will send a letter to the European Union requesting a short delay to Brexit, ahead of the EU summit where she will discuss the delay with other members.
It is thought the delay will not be beyond the end of June. According the to the BBC, former Tory leader Iain Duncan Smith - a prominent Brexiteer - said 90% of Conservative MPs would vote against a longer delay and ignoring their views would leave the party in "deep trouble".
European Commission President Jean-Claude Juncker suggested the EU might postpone any decision on extending the Brexit process until it had "more clarity" from the UK.
"As long as we don't know what Britain will say yes to, we can't come to a resolution," he told the German radio station Deutschlandfunk.
"We will probably have to meet again next week, because Mrs May has not got agreement for anything either in her cabinet or her Parliament."
He again ruled out any further negotiation on the current deal, saying the EU had "already moved intensively towards Britain" and "there isn't any more".