In comments to journalists after the 27 EU heads of state and government gathered in Brussels had endorsed the revised withdrawal agreement for the UK’s departure from the bloc on 31 October, the Socialist Party leader recalled that this is already the fourth agreement reached with a UK government and said that he hoped it really was "the end of the line" in the negotiations.

It would, he said, "be a tragedy, after all this effort," if there was a disorderly Brexit without a deal, "with the very heavy consequences that that would have for everyone.”

Issuing an "appeal" to the UK parliament to approve the Brexit agreement now negotiated, Costa then revealed that earlier, at a meeting of European Socialists that preceded the European Council in Brussels, he took the opportunity to convey his position to the British opposition leader.

"Today, at the meeting of the S & D [socialists and Democrats], I had the opportunity to tell the Labour leader, Jeremy Corbyn, who obviously … each of us has our own internal political contingencies in each of our countries, but that there is a moment where we all have to be able to put the interest of Europe and the general interest above the partisan conveniences of each one," he said.

According to Costa, "it is obviously legitimate that Labour wants early elections" but, he argued, "it is necessary to understand that the time has come when the general interest of Europe, the United Kingdom, the citizens of Europe resident in the UK, of British [nationals] residing in Europe, in what is the normal functioning of the European economy and the British economy, cannot be interests sacrificed to the political will to have elections."

This is, he stressed, "an internal issue for the United Kingdom, the United Kingdom will deal with it. But we cannot all be held hostage by internal policy issues of the United Kingdom. So it is time, once and for all, for the British parliament to correspond to what It has been a patient, continued, persistent effort, of very good will on the part of the EU, to negotiate successive agreements to try to overcome successive rejections."

Asked whether Corbyn was receptive to his arguments, Costa smiled and replied simply that he would see on Saturday, the day scheduled for the vote in the House of Commons on the deal that the government has reached with the EU.

With regard to the assurances that the British prime minister, Boris Johnson, was able to give of being able to get the new agreement through parliament, Costa said in a joking tone that Johnson "did not mortgage his house" on the matter, but simply "gave the assurance that any prime minister can give, which is the assessment he makes of the majority that he has available in his parliament."

On a possible further extension of the date of Brexit if parliament rejects this deal, too, Costa said that this scenario was not on the table; what was on the table is a deal that has everything that merits its being approved, since "the previous one was rejected by Mr . Boris Johnson [as a backbencher] and this one now has been negotiated and approved by Mr . Boris Johnson."

"So this is a happy day,” he concluded. “Let's hope that Saturday is an even happier day and that Sunday allows us to finally start doing what is most important, which is to deal with the future relationship with the United Kingdom.”