Boris Johnson's resounding victory means the Withdrawal Agreement should be passed by the House of Commons quickly.
The European Union have welcomed Boris Johnson's thumping general election victory, calling for the Brexit deal to be ratified as soon as possible with Commission President Ursula von der Leyen stressing that "the time frame ahead of us is very challenging".
EU officials and leaders have however warned Britain against using Brexit to cut tariffs and undercut the bloc.
Speaking to reporters from Brussels after a two-day EU leaders' summit, the new EU chief congratulated Johnson on his victory and said the bloc "expect(s) the ratification of the Withdrawal Agreement to be ended by January".
She said the EU is ready to move to the next phase of the Brexit process, warning that "the time frame ahead of us is very challenging. We will have to work as soon as possible. We will be ready to get the most out of the short period available."
Von der Leyen added that she wants the EU and UK to enter into an "unprecedented partnership" in which relations will be "as close as possible in full respect of our principles".
She stressed that "the level-playing field is of the utmost importance".
"It is also of utmost importance that we care for the 3.5 million European citizens in the UK and therefore we are getting ready now to formulate the mandate that is necessary to start the negotiations and to be prepared from the 1rst of February on to go to work," she went on.
Earlier in the day European Council President Charles Michel had also called on the House of Commons to pass the Withdrawal Agreement "as soon as possible" to provide "clarity" to citizens and companies on both sides of the negotiating table.
"My point is very clear. The EU, we are ready. We have decided what are our priorities. The level-playing field is a very important priority for us. We consider very important to keep this close cooperation with the United Kingdom, to develop the possibility for trade, for economic development but also in other fields like security like defence.
"I hope we will have a loyal negotiation, a good negotiation," he added.
French President Emmanuel Macron, who in the past proved himself to be the most impatient EU leader over Britain's continued political deadlock over Brexit, also expressed his wish for the Withdrawal Agreement to be ratified as quickly as possible after congratulating Johnson.
He praised France's relationship with the UK which he described as "built on battles of our common history" and called for the "closest possible relationship".
He stressed however that the UK would become a competitor and warned that access to the single market will be linked to "regulatory convergence".
"I don't think that you can have a strong relationship with Europe's single market with substantial regulatory differences on climate, environmental, economic or social regulations," he told a news conference in Brussels.
'Flexibility to negotiate'
Johnson's Conservatives have secured 364 of the 650-seats House of Commons, all but ensuring that the newly-reelected Prime Minister will pass his Brexit deal through Parliament easily and quickly.
The majority — the biggest of any Conservative government since the 1950s — also means Johnson will not have to rely on Northern Ireland's Democratic Unionist Party and that the influence of the hardline European Reform Group — led by arch Brexiteer Jacob Rees-Mogg — is likely to be curtailed.
EU sources told Euronews' Shona Murray that although "it’s a tragedy that Remainers were such a divided mess", the strong Conservative majority means that Johnson "has flexibility now to negotiate a decent trade deal."
Irish Taoiseach Leo Varadkar congratulated Johnson from Brussels and stressed that "the next step is to ratify that Withdrawal Agreement which guarantees no hard border between north and south, guarantees the protection of the common travel area and also the fact that British and Irish citizens' rights will be protected."
"And then we go on to the next phase of Brexit which is negotiating a mighty new future economic partnership between the Eu and the UK and I think that can be done."
Varadkar added that he wants a "trade deal or trade deal plus" with the UK which will "insure that we still have a tariff-free trade between Britain and the EU and a set of minimum standards" so that "nobody feels that there is unfair competition, especially when it comes to labour rights or environmental protection".
Other European leaders also offered their congratulations to Johnson, including German Chancellor Angela Merkel who said she looks forward "to working with you for the friendship and strong cooperation between our nations."
Ukrainian President Volodymyr Zelenskiy offered his "sincere" congratulations to Johnson for the victory, adding that he's "willing to work together for the benefit of our peoples, as well as peace and prosperity in Europe".
US President Donald Trump was also among the firsts on Friday morning to congratulate Johnson.
Taking to Twitter, the American leader wrote that "Britain and the United States will now be free to strike a massive new Trade Deal after Brexit"
"This deal has the potential to be far bigger and more lucrative than any deal that could be made with the EU. Celebrate Boris," he added.
During the campaign, the main opposition Labour party had accused the US President of interfering in the election after he told Nigel Farage in a radio interview that it would be "so bad" if Jeremy Corbyn were to be elected. Meanwhile, he had described Johnson as a "fantastic man and I think he's the exact right guy for the times" and said the two of them enjoyed "a great friendship".