Here's what we know about the Turkey-EU spat

As the Dutch go to the polls on Wednesday for parliamentary elections, the Netherland's diplomatic spat with Turkey could amplify rising nationalist sentiment and impact how people vote.

Anti-migrant and anti-Muslim candidate Geert Wilders' popularity has soared, and Dutch Prime Minister Mark Rutte's move to bar Turkish ministers from speaking at public rallies is seen an attempt to expand his voter base.

Turkey's row with several European Union states over Turkish officials campaigning on foreign soil is also likely to impact a different kind of election, one which Ankara has planned for April – a referendum asking the public if it wants to move to a system of governance where the president holds more powers and the prime minister's post is eliminated.

Why are Turkish-European relations in a tailspin?

Turkish citizens have to vote "Yes" or "No" on April 16 to key changes to the constitution. The parliament has already approved amendments that would replace the current form of government with a presidential system.

At home the issue is divisive. The governing Justice and Development (AK) Party has been looking to boost support amid criticism from the opposition.

The new constitution helps political parties form stable governments, say leaders of the governing party. On the other hand, opposition parties say the changes will bolster the president's powers.

Ahead of the referendum, the governing party also wants to woo expatriate Turks who reside in Europe; many of the roughly 3 million overseas voters are concentrated in Germany and the Netherlands.

That may be a minuscule number when compared with the 55 million registered voters within Turkey. But in a tight race, every vote counts.

In the last couple of weeks, the Turkish government attempted to mobilise support from its citizens in various European cities. While Foreign Minister Mevlut Cavusoglu was able to address potential oversea voters in France, Turkey was less successful in other EU countries.

So why were Turkish ministers not allowed to hold rallies?

Turkish ministers were not allowed to address campaign rallies in Germany and the Netherlands for the "Yes" vote.

At least two states in Germany cancelled political rallies organised by Turkish officials in early-March, citing security concerns. President Recep Tayyip Erdogan likened the restrictions to "Nazism."

Chancellor Angela Merkel told Turkey to stop invoking Berlin's Nazi past in criticising cancellations of the ministers' rallies in Germany.

The government of the Netherlands then stopped Cavusoglu from flying to Rotterdam where he was scheduled to address a rally on March 11.

The night didn't end there.

Turkey's Family Minister Fatma Betul Sayan Kaya was forcibly escorted from the Netherlands after she arrived by car to address the crowd instead of Cavusoglu at the consulate in Rotterdam.

The pictures of Dutch police using dogs and water cannons to disperse a crowd of Turkish nationals, who threw bottles and stones, further stoked tensions and invoked more references to Nazism by Erdogan.

Dutch Prime Minister Mark Rutte asked Turkey for an apology for comparing the Netherlands to fascists and Nazis.

Things rapidly spiralled out of control, with Turkey barring the entry of the Netherlands' ambassador and closed its airspace to Dutch diplomats. Turkey also threatened to end the refugee resettlement deal.

Who stands to gain?

Even though Turkey is not a member of the EU, it has close trade and strategic ties with its western neighbours.

But its presidential referendum has coincided with tense times in the Netherlands and Germany, where political parties in power are under pressure to appear tough on migrants.

The Netherlands is especially on edge as some polls showed Wilders doing better than expected.

Germany's federal elections are due in September and face similar concerns about anti-migrant right-wing candidates gaining electoral ground.

In addition, the EU, including Germany, has been sharply critical of Turkey's mass arrests and dismissals of people suspected of links to the coup.

However, Germany denied any political motive for cancelling rallies. Merkel said Berlin will continue to allow Turkish politicians to campaign in Germany for the referendum, provided German law is respected.

If European governments thought keeping the Turkish government from courting the predominantly Muslim Turkish bloc in Europe would help stem the far-right, Wilders gaining popularity says otherwise.

The anti-Turkey narrative in Europe has also stirred public emotions in Turkey, right before the referendum.

Is there more to it than meets the eye?

Turkey's relations with the EU countries have been rocky for quite some time. Ankara says its European peers have used different pretexts to block its entry into the EU.

After the 2016 failed coup attempt in Turkey, Erdogan's aides complained that European leaders were slow in expressing support. The Turkish government has repeatedly complained that the EU, instead of showing support, has been criticising mass arrests of people accused of facilitating last July's coup attempt.

Another point of contention is Germany giving permission to organisations accused of being affiliated with the PKK to run political campaigns there. The PKK is considered a terror organisation by Turkey, the US and the EU, and has been held responsible for killing thousands of Turkish citizens.

Can things escalate between Turkey and the EU states?

Turkey says it has suspended high-level diplomatic relations with the Netherlands. Turkish and German leaders have exchanged harsh words, accusing each other of stoking sentiments for political gains.

Yet, all sides have called for restraint. All three countries are part of a NATO alliance that encourages military and economic cooperation among members.

The Dutch prime minister called his Turkish counterpart to apologise for the detention of Turkish diplomats by police.

Turkish and German leaders haven't taken their differences beyond verbal attacks.

Since Turkey plays a crucial role in stemming the flow of migrants to Europe where the refugee influx is a politically explosive issue, the war of words is expected to remain more rhetorical as countries figure out how to walk back the diplomatic spat.