EU Commission President Ursula von der Leyen said the bloc hopes to be the UK's "best friend" going forward but that "with every choice comes a consequence".
European Commission President Ursula von der Leyen said on Wednesday that striking a comprehensive EU-UK trade deal before the end of the year is "impossible," warning that compromises will be needed as she outlined her vision for the future relationship.
Von der Leyen's speech in London to her former alma matter — she attended the London School of Economics and Political Science in the 1970s — is entitled "Old Friends, New Beginnings: building another future for the EU-UK partnership".
You can watch her address in the video player, above.
After the speech, the EU chief met Prime Minister Boris Johnson in Downing Street.
'Best of friends and partners'
The EU's top official opened her address by praising the UK for being "big-hearted, proud and patriotic, kind and generous in spirit" and said she "truly fell in love with this city and this country" when she was a student at the LSE.
She also paid tribute to former British Prime Minister Winston Churchill for making "the best case for a united Europe" after World War II and to all the British civil servants whose work has since helped shape the EU.
She stressed that "when the sun rises again on February 1st, the EU and the UK will still be the best of friends and partners. The bonds between us will still be unbreakable."
She added that now is the time for "the best of friends and oldest friends to build a new future together", adding however that "the truth is that our partnership cannot and will not be the same as before".
"And it cannot and will not be as close as before — because with every choice comes a consequence. With every decision comes a trade-off," she continued.
'No compromise' on integrity of EU customs union
The EU, she said, is "ready to design a new partnership with zero tariffs, zero quotas, zero dumping" and a "partnership that goes well beyond trade and is unprecedented in scope".
But, she went on, "without a level playing field on the environment, labour, taxation and state aid, you cannot have the highest quality access to the world's largest single market" and that "without the free movement of people, you cannot have the free movement of capital, goods and services".
"The European Union's objectives in the negotiations are clear. We will work for solutions that uphold the integrity of the EU, its Single Market and its Customs Union. There can be no compromise on this," she said.
She also described the negotiation schedule as "tight" given that the UK is officially scheduled to exit the bloc on January 31 and Johnson has previously stated that he would not extend the transition period past December 31, 2020.
'Collaboration over isolation'
Von der Leyen said it would be "impossible" to get a comprehensive deal, stressing that "you cannot expect to agree on every single aspect of our partnership" in the next 11 months and that "we will have to prioritise." She also emphasised that when it comes to policy areas including climate change, fisheries, data protection, energy and security, no country can go it alone.
Citizens' rights are "a pressing issue", she said, but the "good news" is that citizens currently living on both sides of the English Channel will keep the same status for the rest of their lives.
She then appealed to younger generations to "make a success" of the future partnership between the EU and UK.
"You can choose collaboration over isolation, you can shape your continent's destiny, you can hold your governments accountable, you can refuse to be satisfied with the status quo and can turn things into how they should be," she said.
"There will be tough talks ahead and each side will do what is best for them. But I can assure you that the United Kingdom will always have a trusted friend and partner in the European Union.
"This is the story of old friends and new beginnings," she added.