With one week until the re-run of Austria’s Presidential election, the two candidates vying to become the country’s head of state have clashed in a heated debate over EU membership, immigration and foreign relations.

Ahead of Sunday's (December 4) election, Green-backed candidate Alexander Van der Bellen and the far-right Freedom Party's (FPO) Norbert Hofer faced off in a TV debate, with van der Bellen accusing his rival of stirring insecurity by threatening to pull out of the EU.

"The FPO has been toying with Austria's exit for 20 years. Many politicians in Europe are worried that the mere speculation could trigger… an avalanche of right-wing populism," the 72-year-old said during the debate, broadcast on ATV.

what will be the #Austria equivalent to Brexit, Grexit etc in the media, if Hofer wins and holds EU #Referendum #Auxit too hard to pronoune? — Colin (@Caflockton) November 24, 2016

​The accusation came after Hofer earlier said he would call a referendum on Austria's EU membership if Turkey joined the bloc, or if Brussels tried to further integrate member states and centralize power.

Hofer has since backtracked on these claims, saying: "There won't be an 'Auxit'. I've repeatedly said that I want a positive development of the EU."

Trump, Merkel on the Agenda

During the debate the two also clashed over Austria's foreign policy, with disagreement over what is in the country's best interests.

Van der Bellen stressed the importance of Austria's relationship with its biggest trade partner, Germany, calling on the EU to unite amid potential threats from Moscow, and even Washington under Donald Trump.

#Hofer held a very reserved speech in contrary to his party's political agenda; was speaking of humanitarian ways for refugees. #IHEID — Philipp Nigitsch (@philippnigitsch) October 20, 2016

​"The most important thing is the solidarity between member states, otherwise we won't be able to assert ourselves in the face of Russia or the United States," he said.

Van der Bellen has been an outspoken critic of Trump, taking aim at the President-elect's rhetoric on immigration and women by saying that many EU countries were feeling "anxious" about his arrival in the White House.

An intellectual having to debate with a political doofus: Hillary debating Trump, reminds me of Van der Bellen debating Hofer. — nicolas (@nicolasmha) June 8, 2016

​However Hofer, who's FPO has gained support by taking a hardline stance on immigration and criticizing what it perceives to be political elites, took a different view on the Trump issue, criticizing Van der Bellen for his attacks on the incoming president.

"It is not clever to describe a president as a rabble rouser," he said in a swipe at the Green-backed candidate.

It wasn't just on Trump where the two differed in terms of foreign policy.

​Hofer denounced German Chancellor Angela Merkel for "causing serious damage to Europe" through Germany's open-door refugee policy, saying that it resulted in a number of "terrorists" being able to trek through Austria en route to other parts of the continent.

Meanwhile he also called for Austria to seek closer ties with central and eastern European states, defying Van der Bellen by saying that Vienna should mend ties with Russia, which is still currently facing EU sanctions.

Vote Too Close to Call

The December 4 vote comes after the result of May's presidential election was annulled due to a Constitutional Court ruling that found there was a breach in electoral procedural protocol.

Van der Bellen won the May vote with a paper-thin majority of 50.3 percent, with postal votes from many Austrian expats living abroad helping him over the line.

Polls in Austria for #bpw16 not making my job of forecasting the election much easier, still a toss-up pic.twitter.com/28WqL2i57M — Pepijn Bergsen (@pbergsen) October 24, 2016

​While the position of Austria's president is largely ceremonial, many in the EU establishment are concerned about a potential FPO victory, as it will give Europe its first far-right head of state since World War Two, amid a rush of Euroskepticism across the continent.

Sunday's vote is expected to go down to the wire once again, with polls suggesting the race to too close to call.