Boris Johnson has said there is no reason why the outline of a Brexit deal cannot be sealed by the end of July, after he asked EU leaders at a video summit to “put a tiger in the tank” of stalled talks. In a boost for the prime minister’s plans to secure a deal by the end of the summer, the EU leaders agreed to strive to find early common ground on trade and security to avoid unnecessary economic chaos next year. However, there were immediate signs of tensions on the horizon, with the president of the EU council, Charles Michel, tweeting afterwards that he would accept a “tiger in the tank”, but that the EU would not agree to a “pig in the poke” and never accept an agreement that went against the interests of the union. As well as Michel, the EU was represented at the hour-long video summit by Ursula von der Leyen and David Sassoli, presidents of the European commission and parliament respectively. Johnson was joined by the chancellor of the Duchy of Lancaster, Michael Gove, his chief Brexit negotiator, David Frost, and the ambassador to the EU, Sir Tim Barrow. The prime minister later told reporters he was optimistic despite talks having stalled last week. “It is very clear what we need to achieve. I don’t think we’re that far apart, but what we need is a bit of oomph in the negotiations, and I was pleased that Ursula von der Leyen [and other EU officials] all agree … There is no reason why we shouldn’t get this done in July.” It is understood that the prime minister told the three EU leaders he was committed to the political declaration, after weeks of criticism from Brussels that he had turned away from the document that he signed last October. While Johnson is looking for firm progress within weeks, the EU is more relaxed about striking a deal in the autumn. The EU chief negotiator, Michel Barnier, has said 31 October is the final deadline, and EU officials have said they will work to the last possible moment to reach a deal. After the video meeting, the mood among EU officials was upbeat, although serious differences remain between the two sides, especially over the “level playing field” conditions attached to a free trade agreement, fisheries, police cooperation and governance of the future agreement. In a joint statement after the meeting, both sides acknowledged that talks had stalled after four rounds. But they added that they must move forward for the sakes of citizens on both sides. “The parties agreed nevertheless that new momentum was required. They supported the plans agreed by chief negotiators to intensify the talks in July and to create the most conducive conditions for concluding and ratifying a deal before the end of 2020. This should include, if possible, finding an early understanding on the principles underlying any agreement,” they said. In the meeting, they also “underlined their intention to work hard to deliver a relationship that would work in the interests of the citizens of the union and of the United Kingdom”, an indication that both were still aiming for a comprehensive and ambitious deal. Johnson said the UK would continue to insist there was no role for the European court of justice, underlining assessments on both sides that finding a mutually agreeable international arbitration system remains one of the most difficult issues to resolve. After the meeting, Von der Leyen acknowledged that Gove had formally notified the EU at the joint committee meeting that the UK would not be seeking to extend the transition period. “We noted the UK’s decision not to extend the transition period and agreed to deliver the best deal for our citizens,” she tweeted.