Prime Minister Theresa May is trying to win over MPs, who have so far voted against her Brexit deal with the threat that the only other option is a long delay to leaving the EU.
The European Commission said it would be down to the bloc "to consider such a request, giving priority to the need to ensure the functioning of the EU institutions and taking into account the reasons for and duration of a possible extension".
DUP deputy leader Nigel Dodds said lengthy talks on Friday with senior ministers including Chancellor Philip Hammond were "constructive" and there was a "renewed focus" from the Government on addressing their concerns.
May has said she will hold another vote next week on her deal, although lawmakers have already rejected it twice.
MPs voted to extend Article 50 until 30 June by a majority of 412 to 202.
Article 50 was triggered on March 29, 2017 with the United Kingdom scheduled to leave at 11pm United Kingdom time later March 29, 2019.More news: Google Foldable Phone Patent Surfaces Online; See Details
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A no-deal Brexit and a second referendum appear to be taken off the table however.
Any delay will require the agreement of all other 27 European Union members, with talks about possible conditions for an extension to take place before next week's European Union summit, which begins on Thursday.
Barry Lockey, who arrived in Sunderland carrying a flag with the message "Get Britain out: Time to leave the EU", said that the event is about supporting democracy.
And it could also use the same tactics to fend off the requirement to hold EU Parliament elections in May, however long the Article 50 extension is.
EU Council President Donald Tusk, who coordinates the strategy of European leaders, said in a Twitter post Thursday that he wants government chiefs to be open to a "long extension" if Britain decides to "rethink its Brexit strategy and build consensus around it". But the failure of everyone else to come up with anything close to an alternative plan means that her deal remains the most likely outcome.
"You don't just have a short, technical extension to our membership of the European Union, you nearly certainly need a significantly longer one to find a time for parliament to come to a majority verdict", he told BBC radio.
After three dramatic days in parliament this week, lawmakers voted on Thursday to have the government ask the European Union for a delay beyond the date Britain is scheduled to leave - March 29. And more Tory MPs now opposing May's Brexit deal have told party whips they would back it if the prime minister announced she would quit this summer.