A series of potential scandals is plaguing the far-right Alternative for Germany (AfD) party, overshadowing the launch of its campaign for next month’s elections for the European Union’s legislature.

Germany’s biggest opposition party, which swept into the national parliament two years ago after focusing its campaign on curbing migration, is struggling to explain a number of murky donations prominent party members received in recent months, some of them from abroad.

In addition, Germany’s public broadcaster ZDF last week quoted emails between Russian officials appearing to predict the 2017 election of one of the party’s lawmakers, Markus Frohnmaier, to the German parliament and suggesting he would act as a puppet for Moscow.

Mr Frohnmaier, who has publicly supported Russia’s annexation of Crimea, denies the claim.

A poll published Sunday by the German weekly Bild am Sonntag found the party’s support has fallen to 12 per cent — its lowest value in years.

The far-right politicians winning power across Europe Show all 7 1 /7 The far-right politicians winning power across Europe The far-right politicians winning power across Europe Viktor Orban – Hungary, Fidesz The Prime Minister of Hungary has threatened to shut down NGOs that help refugees; run a state backed hate campaign against George Soros and removed constitutional checks and balances. He said: 'We have replaced a shipwrecked liberal democracy with a 21st century Christian democracy' Reuters The far-right politicians winning power across Europe Matteo Salvini – Italy, Lega The leader of Italy’s junior governing party has pledged to deport 500,000 irregular migrants; stated joining the euro was a mistake and wants to end sanctions against Russia. He said: 'The only antidote to racism is to control, regulate and limit immigration' AFP/Getty The far-right politicians winning power across Europe Heinz-Christian Strache – Austria, FPO The deputy prime minister of Austria wants to drive Islam out of public life in Austria; has threatening mosque closures and wants to end sanctions against Russia. He said: 'Let us put an end to this policy of Islamisation as soon as possible' AFP/Getty The far-right politicians winning power across Europe Marine Le Pen – France, Front National The runner-up in the French presidential election wants policies to favour ‘native’ French; has stated she would hold an EU referendum and wants to deport irregular migrants. She said: 'I’m not offended when I hear President Donald Trump say "America first". In fact, I want America first for the American people, I want Britain first for the British people and I want France first for the French people' AP The far-right politicians winning power across Europe Janez Jansa – Slovenia, Slovenian Democratic Party The leader of Slovenia’s largest party says the country is run by a secretive former communist cabal; has appointed political allies to press agencies and was sent to prison for alleged corruption which was later overturned by the Constitutional Court. He said: 'Our party puts Slovenia, Slovenians first' Reuters The far-right politicians winning power across Europe Alexander Gauland – Germany, AfD The leader of the first far-right party in the Bundestag in decades says Islam is not a part of Germany; wants a ban on public Islamic symbols and wants to leave the euro. He said: 'A German or English football team hasn’t been German or English in the classical sense for a long time' Alamy The far-right politicians winning power across Europe Jarosław Kaczynski – Poland, Law and Justice The chairman of Poland’s governing party says migrants spread infectious diseases; wants to ban gay people from being teachers and has sought to implement constitutional changes to give government more power over courts. He said: 'It is absolutely clear a homosexual should not be a teacher' Kacper Pempel/Reuters

The survey of 2,355 respondents between 28 March and 3 April asked about national elections, but recent polls for the 23-26 May European vote have reflected similar or lower support.

Over the weekend, Alternative for Germany’s lead candidate for the 26 May vote dismissed allegations against his party as conspiracy theories and insisted it has “many good allies” in other European countries.

Speaking Saturday at an EU election rally in Offenburg, Joerg Meuthen said AfD would work with the Austrian Freedom Party, Italy’s anti-migrant League party and the Fidesz party of Hungarian Prime Minister Viktor Orbán to create “a new alliance of conservative, freedom-minded and patriotic forces of reason” at the European level.

Mr Meuthen himself has come under scrutiny over free election ads he and others in the party received from a Swiss-based PR agency.

AfD’s co-leader Alice Weidel received more than 130,000 euros (£112,000) from Switzerland ahead of the 2017 national election — a possible breach of German electoral law.

German news agency dpa also quoted Mr Meuthen calling the claims about Mr Frohnmaier’s ties to Moscow “total nonsense” Saturday.

Public broadcaster ZDF and weekly Der Spiegel cited a strategy paper supposedly written by Russian government officials to bolster Russia’s interests abroad.

The 2017 paper describes Mr Frohnmaier, 28, as an asset for Russia who “will be absolutely under our control”, according to the reports.

ZDF and Der Spiegel said the document was provided to them by an organisation close to exiled billionaire Mikhail Khodorkovsky, a fierce critic of the Kremlin. Its veracity couldn’t be independently verified.

Frohnmaier told ZDF that he couldn’t imagine who might have written about him in that way. “I ran to represent German interests. And that’s what I’m doing,” he told the broadcaster.

Since his election, Mr Frohnmaier has vocally supported Moscow’s position on Crimea, which Russia seized in 2014 in a move that Ukraine and most of the world views as illegal.

CCTV shows moment far-right German MP is beaten unconscious by masked assailants

In an interview with Kremlin-funded broadcaster RT, Mr Frohnmaier said that Crimea “is now Russian Crimea”.

AfD has been wracked by scandals and infighting since its founding in 2013. Several senior figures have left the party, including two of its former leaders.

AfD’s parliamentary co-leader in the state legislature of Bavaria announced he was quitting, too. In a statement, Markus Plenk, cited the party’s drift to the right as a reason for his departure.