Theresa May has written to the European Union to request a further delay to Brexit until 30 June.
The UK is currently due to leave the EU on 12 April and, as yet, no withdrawal deal has been approved by MPs.
The prime minister has proposed that if UK MPs approve a deal in time, the UK should be able to leave before European Parliamentary elections on 23 May.
But she said the UK would prepare to field candidates in those elections in case no agreement is reached.
EU leaders must agree unanimously whether to grant an extension to the Article 50 process, under which the UK leaves the EU, after MPs repeatedly rejected the withdrawal agreement reached between the UK and the bloc.