If you thought the Brexit referendum was a knife edge vote, spare a thought for the Moldovans. The country wedged between Romania and Ukraine held an EU referendum on Sunday where the Yes campaign won with 50.5 percent against 49.5 percent. This result is not the last word. Moldovans did not actually vote to join the EU, only to change their constitution to make that possible. The big referendum is yet to come.

Or maybe not. For the EU and for Maia Sandu, the pro-EU president, the result is a disaster. She needed more support. The previous polls suggested a large majority in favour of EU membership. Sandu immediately accused the Russians for meddling as the No campaign took a lead. The Yes campaign prevailed in the end only because of the votes by the country’s relatively large number of expats, many of which live in Romania, Ukraine and Russia.

Moldova is a country at the intersection of two big European cultures, the Russian and the Romanian. This part of the world was once known as Bessarabia, a region that used to be a little larger than today’s Moldova. With the Treaty of Bucharest in 1812 that ended the Russia-Turkish war, Bessarabia was annexed by Russia. A hundred years later after the Russian Revolution, the region reconstituted itself as the Moldovan Democratic Republic as part of the Soviet Union. During the Soviet period, the country switched to the Cyrillic alphabet even though its language is a subdialect of Romanian, a Latin language. After the collapse of the Soviet Union, Moldova became independent and switch back to the Latin Alphabet. What is left from the old period is a bitter divide between Moldovan and Russian speakers. Transnistria, a semi-autonomous Russian enclave in the east of the country, is the most visible example of that divide. Russian native speakers nowadays constitute only about 10 percent of the population, but this minority strong enough to produce knife-edge votes as we had on Sunday.

For the EU this is the most serious setback since the Brexit vote. Governments in Europe’s south-east are queuing up to join – there are nine candidates including Moldova and Ukraine. Another candidate, Georgia, held parliamentary elections in another setback for EU enlargement. The governing, Georgian Dream, came first, amid reports of election fraud. The  current prime minister, Irakli Kobakhidze, campaigned with the message to stop Georgia being drawn into Russia-Ukraine war. I am wondering whether Russia’s recent military successes in Ukraine, and especially the switch to a war economy, may have reinforced that message.

I also suspect that the visible decline in the west’s support for Ukraine may have been a factor for Georgian voters. Putin invaded Georgia in 2008. If he did so again, the west cannot be relied upon to fight another proxy war in the region. We should not take pro-Western attitudes for granted in this war-ravaged region.

My social media feed is full of pictures of brave young demonstrators, draped in the European flag, on the streets of Tbilisi. But as we found elsewhere in Europe, the young activists in cities are usually not representative of countries with large rural populations.

The EU granted Georgia, along with Ukraine and Moldova, official candidate status last December, but the route will be arduous for all three of them. All have Russian communities and voters more inclined to support Russia than the West.

For Russia to meddle in another country’s affairs is a lot easier when a part of that population speaks Russian. The Moldovan authorities claim that Russia paid €15 million to 130,000 people as a bribe to vote No in the referendum. This is a little over €100 per person. In a poor country like Moldova, this is a lot of money for many people. The bars or Russian meddling are very low, and that will continue to be the case.

In its enthusiasm for enlargement the EU also tends to overestimate its own popularity. Enlargement is the only discernible pillar of the EU’s geopolitical strategy, but the EU is hardly in control of events.

The EU may also be underestimating resistance from existing members once the costs of the enlargement to economic destitute regions become clear. So far, only Viktor Orbán, the Hungarian prime minister, has threatened to block Ukrainian EU membership. He will be gone one day. Where I see the real opposition to the membership is from Poland and other net recipients from the EU budget. Poland is by far the largest, a status it would have to relinquish as a price for EU enlargement. It is one thing to be pro-European when you get money, but quite another when you do not.

This is why I think hopes of rapid and massive EU enlargement are vastly overblown. The EU and its supporters have forever been suffering from an optimism bias. But this is not justified by recent events. The European economy is stagnating and falling behind the US and China. I cannot see a scenario in which the EU would formally break up, or even lose more members, but there is a real chance that the EU might fade as a political force and lose its shine as a region of economic prosperity. That, in turn, will further weaken the argument for membership.