* EU chief wants summit in Romania on day of Brexit
* Focus in March 2019 must be EU future, not Britain
* Juncker challenges Merkel, Macron ideas on euro
* EU officials believe he can win Paris, Berlin backing
STRASBOURG, Sept 13 (Reuters) - Transylvania may not seem everyone's idea of a fun weekend away to get over a painful break-up but that is Jean-Claude Juncker's prescription for EU leaders to cope with the blues on the day Britain walks out.
Sibiu, the picturesque historic home of Romania's ethnic Germans, will be just the place for the other 27 national leaders to make a public show of unity on Saturday, March 30, 2019, the European Commission president told EU lawmakers on Wednesday in his annual State of the European Union address.
His proposals for a more united bloc without Britain face scepticism from many governments. But the EU's chief executive has, officials said, calculated that expanding the euro zone and deepening its cooperation can win support from Angela Merkel and Emmanuel Macron, leaders of the founding powers France and Germany, and heal rifts with newer, poorer members in the east.
His mention of Brexit brought cheers from UK Independence Party members in Strasbourg. They scoffed at Juncker's warning that Britons would soon regret leaving and said UKIP would look forward to that weekend 18 months hence to celebrate Britain's "liberation" from what they call EU diktat from Brussels.
But aides say Juncker believes many of the 440 million other Europeans will only truly wake up to the fact the second-ranked economy is leaving pretty much around when it actually happens.
And to reassure them at what Juncker said would be "a very sad and tragic moment", their leaders should plan a get-together in Romania, one of the newest, and poorest member states, which just happens to be the rotating chair of the EU in early 2019.
A rich cultural heritage -- Juncker noted that German-speakers like himself know it as Hermannstadt, capital of Transylvania's centuries-old Saxon community -- makes Sibiu a good spot to celebrate the Union of Europe's diverse peoples.
"The whole idea on that day is to focus on...matters to come for the Union, not on the ones who are leaving," one senior EU official said of the Sibiu summit, which was welcomed by Romanian President Klaus Ioannis, a former mayor of the city.
And if hostile British commentators might be tempted to link the Transylvanian venue to a view of the EU as a bloodsucking vampire on the British taxpayer, Romanian locals insist their town has little to do with the region's Dracula legend.
Aside from altering the atmospherics of what will certainly be a historic weekend for the European Union, the success of Juncker's vision for Sibiu in 2019 will depend on how national leaders respond to the proposals he sketched out on Wednesday.
Most strikingly, the former Luxembourg premier who will step down in autumn 2019, wants to use the departure of the Union's opter-out-in-chief, Britain, to end a culture of states picking and choosing which bits of integration they want - for themselves and others - and to bring all 27 or more nations in to the euro currency zone, Schengen travel area and bank union.
In a speech that carefully balanced indirect criticisms and praise for different leaders across the bloc, he slapped down Macron's embryonic proposals for a separate euro zone budget and plans to push ahead with deeper integration that could leave non-euro countries, especially in the east, on the EU's fringes.
The German government, preparing for an election in two weeks that should hand Merkel a fourth term, is sceptical of Macron's plans but is also likely to be wary of the ambition of Juncker's proposals. Its initial reaction was restrained.
EU officials, however, play down the idea that Juncker is making for a head-on confrontation with Merkel and Macron when he sets his face against a "multispeed Europe" that the veteran EU dealmaker believes bears the seeds of the EU's unravelling.
Rather, Juncker sees his idea of a euro zone covering the whole EU, with its budget part of the overall EU budget and run from the existing Commission, as a practical application of the kind of suggestions Macron and Merkel seem to support but on which their administrations have offered little concrete detail.
At the same time, EU officials argue, past attempts by Paris and Berlin to force a lead on integration, such as by Merkel and then president Nicolas Sarkozy at the height of the euro zone crisis in 2011, failed to gain traction. Juncker, they say, will try to persuade them that his broader approach is more viable.
Nonetheless, his suggestion that the likes of Poland and Hungary, run by deeply eurosceptic governments, should join the strictures of the euro zone is unlikely to win rapid support in Warsaw or Budapest. Juncker's argument is, however, that if they refuse offers and pressure to join, they cannot then complain about being treated as "second class" members of the Union.
Juncker, 62, said he had despaired of the EU at times but wants Sibiu to offer EU voters something other than Brexit to wake up to, two months before a European Parliament election.
The biggest challenge to achieving his long list of ambitions by then will be overcoming entrenched national interests: "Democracy is about compromise," he said in a blunt warning to the squabbling leaders he wants to come together in Transylvania. "Europe cannot function without compromise." (Additional reporting by Luiza Ilie in Bucharest; editing by Ralph Boulton)