Just as the migration crisis eases, Berlin and Paris brace themselves for another blow - the possibility of the UK leaving the EU. The Ukraine crisis is almost forgotten, but those Dutch who could be bothered to vote have rejected an ever-growing union. So it is hardly the best time for an old horror to remerge - Euro Crisis 2. But that is what is on the cards. Mutterings from Portugal, news from Spain, Italian woes and Greeks refusing to bear gifts to Berlin all point towards a difficult summer.

Like the final shot of a horror movie, a creepy hand thrust up from the ground, there is new evidence the monster never died. Of course, we all knew the euro crisis was never solved, merely shelved. But German-driven austerity is becoming more irksome to governments elected to oppose it, and the European Central Bank (ECB) is taking notice, to the dismay of politicians in Europe's biggest economy.

Nearly everyone agreed the euro was unsustainable without big changes. That is where the unity ended. Everyone had different solutions, none of them, to my mind, very politically palatable. If the euro crisis returns, it will be because policy makers can't or won't face the conundrum at the heart of the single currency - the shackling together of very different economies with very different needs. It is a north-south divide which boils down to Germany against the Latin countries. Even as it imposes more pain on its people, through tax rises, the Syriza government is unwilling to knuckle under and give in to demands for yet more cuts to service its debt.

The troika - the International Monetary Fund (IMF), the European Commission and the ECB - can't agree on what they should do anyway. The IMF prescribes more debt relief, but doesn't want to finance it. If it were to walk away, Greece would be back in the critical ward. This was always going to be an epic tussle. The Greek government is, of course, in a tricky position, elected first to oppose austerity, then, a few months later, to implement it.

But a devastating Wikileak has poured fuel on the fire. It appears to show the IMF pondering a plot to crash the Greek economy. It all makes for an interesting meeting of eurozone finance ministers. A new crisis could be just a couple of missteps away. The left are drawing broad lessons from the leak. Paul Mason, unleashed from the constraints of broadcasting neutrality and its linguistic restraints, has suggested this proves the global elite don't care about real people.

With the mood as it is, few are proposing a new EU treaty to further fiscal and monetary integration. The logic is impeccable, but it is a solution that is in stark contrast to an apparent public desire for less, not more Europe. Policy makers see it as an inevitable step - they just can't say when it would be practical.

Brexit cheerleader Johnson spoke out as infighting broke out among senior figures in the 'Leave' campaign after Obama's devastating intervention. Some privately admitted they fear they are heading for defeat in the referendum on June 23. Prominent pro-'Leave' Tory MP Peter Bone said: 'Our message is being drowned out by the Government.' And one 'Leave' official said: 'We had no idea Boris was going to attack Obama so provocatively. It was a misjudgment. He must stop going off-piste.'

Obama's intervention is seen as a potential game-changer in the referendum campaign, with some 'Remain' supporters predicting a decisive 60-40 victory. Respected poll expert Professor John Curtice said yesterday that the 'Remain' camp made 'significant progress' last week but the race was 'far from over'.

Johnson had riled Obama almost before he arrived in the UK, saying the 'part-Kenyan' President had removed a Churchill bust from the Oval Office because of his 'ancestral dislike of the British Empire'.

Obama responded by demolishing Johnson's claim that Britain could quickly cut its own trade deals with the US.

Mr Johnson told The Mail on Sunday last night: 'Barack Obama is entitled to his view… but it is ridiculous to warn that the UK will be at the back of the queue for a free trade deal.' And he pointed out the only reason the UK hadn't already got a trade deal with America, was because we were in the EU, which hampered negotiations. And in a direct challenge to Obama he said: 'It is very weird that the US should be telling the UK to do something they would not dream of doing themselves.'

In a strongly worded rant, permabear Albert Edwards pinned the blame on central bankers for low interest rates and “virtual” quantitative easing (QE) programmes. Central banks across the world are currently dishing out near and even sub-zero rates and QE programmes in a battle to stimulate inflation and growth.

However Mr Edwards argued as well as failing to help normal people, monetary policy is making the rich richer and stirring anger and resentment among normal people. He argued a weak economy forced people to turn to populist parties across Europe, echoing comments by German finance minister Wolfgang Schauble, who last week claimed the ECB’s policies were encouraging the rise of extremist political parties in Germany.

Mr Edwards said: "The people are angry and they are lashing out" adding that voters are "rejecting the establishment political parties and candidates at almost every electoral turn and seeking out more extreme alternatives at both ends of the political spectrum. Central bankers are surely taking us down the road to perdition."

Already unnerved by negative interest rates and the permanent outvoting of the Bundesbank in the monetary decisions of the European Central Bank, senior German officials show intense nervousness about the consequences of a so-called Brexit from the EU. The fear in Berlin is that a UK withdrawal would deprive Germany of a key economic and political ally at a time of great nervousness over Europe’s future.

In particular, it would leave the Germans exposed to the combined forces of France, Italy and Spain, the biggest economies in the economic and monetary union after Germany, all ill-disposed towards German interests. This would be an intriguing and unsettling rerun of the “nightmare of coalitions,” referring to the feared hostile combination of European powers that haunted Otto von Bismarck, the first chancellor of united Germany, in the closing decades of the 19th century.

This time, the peril comes not from outside but from inside an alliance of neighboring states. It would also strengthen forces inside Greece calling from Athens to withdraw from EMU: instead of more European unity, a gradual process of disruptive unraveling would be the result.

One familiar example was the way in which he tried to portray Winston Churchill as “the father of European unity”. As usual, this could only be done by glossing over the crucial difference between the vision of a “United States of Europe” put forward by Churchill after the war, which led to the Council of Europe, and that promoted by Jean Monnet, the true “father of Europe”, which was to lead eventually to the European Union.

Churchill’s vision of a “United States of Europe” was based on intergovernmental co-operation, in which, as he repeatedly made clear, he saw no direct part for Britain. Monnet’s, put forward in the declaration he wrote for Robert Schuman in 1950, was for a wholly new “supranational” form of government, with the power to overrule the wishes and interests of nation states.

Churchill was vehemently opposed to this, as when he said of Monnet’s proposal for “a supranational authority”, in the Commons on June 27 that year: “It is quite certain that we could not agree to become members of it.”

Obama's trip - to open an industrial technology fair and hold talks with Chancellor Angela Merkel and other European leaders - was intended to lend momentum to flagging efforts to see the world's biggest trade pact finalised this year.

On a visit to London on Saturday, Obama sought to address sceptics' fears head-on, admitting that some past trade agreements had "served the interests of large corporations and not necessarily of workers in the countries that participate in them".

The Trans-Atlantic Trade and Investment Partnership (TTIP) has run into major opposition, not least in Europe's top economy Germany, where critics have raised the spectre of eroding ecological and labour market standards and condemned secrecy shrouding the talks.

Just 17 percent of Germans say they support TTIP, according to a Bertelsmann Foundation poll of more than 3,000 people published Thursday, well down on the 55 percent registered two years ago.

During the same period, firm opposition to the pact rose to 33 percent from 25 percent. The picture in the United States is hardly more promising. The "Yes" camp has shrunk to 15 percent from 53 percent, while nearly half - 46 percent - say they feel too ill-informed to have an opinion.

Public support has collapsed right across the EU’s 28 member nations, said Mr Juncker, who is European Commission President. In an astonishing confession of failure, he added: “We are no longer respected in our countries when we emphasise the need to give priority to the EU.”

Campaigners for an EU exit said Mr Juncker’s confession proved the UK will be better off out. Matthew Elliott, chief executive of the Vote Leave campaign group, said: “Even the Eurocrats admit the EU isn’t working for Europe." His remarks, in a speech in Strasbourg, were being seen last night as recognition of public revulsion at the EU ahead of Britain’s in-or-out referendum on June 23.

Tory MP Craig Mackinlay said: “Jean-Claude Juncker is right that the EU is unpopular and too interfering. It has lost respect. He also forgets to mention that it costs too much – not least due to his £250,000-a-year salary – and is incapable of dealing with global challenges such as the migration crisis.”