Ursula von der Leyen has found herself in hot water over her participation in a party political video on behalf of the ruling HDZ party in Croatia.

The European Commission President appeared briefly in the video to deliver the words 'Sigurna Hrvatska' or "a safe Croatia" on the eve of the country's parliamentary elections. This was not a Covid-related message, but the HDZ election slogan.

Ms von der Leyen was joined on the video by the Tánaiste and Minister for Enterprise, Trade and Employment Leo Varadkar, as well as other party leaders from the centre-right European People's Party (EPP) across Europe, including the former President of the European Council Donald Tusk and the current Austrian Chancellor Sebastian Kurtz. All delivered the same 'Sigurna Hrvatska' slogan.

It is customary for party leaders and senior figures from the main political families in Europe to lend their rhetorical support during election time, and all high-profile figures, from the right, left and centre, gather at regular political group summits to formulate policy and catch up on national positions.

Ursula von der Leyen was a longstanding EPP stalwart as a member of Germany's centre-right CDU party. However, what is different now is that she is supposed to be strictly neutral as Commission president.

The problem is that von der Leyen delivered what was taken as a message of support to the Croatian Prime Minister Andrej Plenković in front of the EU flag and on the corridor of her office in the Commission's Berlaymont headquarters.

The video was released on Twitter by the HDZ party on 4 July, and by Sunday evening there was a torrent of criticism on social media. Von der Leyen's spokesman Eric Mamer took to Twitter on Sunday night to say that President von der Leyen had "recorded a short sound bite for use in a video involving a number of EPP politicians".

"It was meant as a contribution in her personal capacity. Regrettably, this was not made clear in the final version of the video," he added.

However, the HDZ did not withdraw the video. It was still circulating by the time Mr Mamer faced a barrage of questions from reporters during the Commission's daily news conference at midday today.

Mr Mamer said that Ms von der Leyen had acknowledged that any message of a political nature must "absolutely respect" the rules of the EU code of conduct. He said the video had been shot on Friday at the request of the Croatian Prime Minister's office, "alongside a whole series of other video messages that the president was in the process of recording".

Mr Mamer conceded: "Mistakes were made and the important thing is to make sure that such mistakes are not repeated". However, there was no apology. Instead, Mr Mamer appeared to criticise the HDZ party for adding the strap "European Commission President" over von der Leyen's contribution.

The affair looks like it has several days to run. "With her show of partisanship, she is gambling away trust and thereby damaging the office," German Social Democrat MEP Jens Geier told the AFP news agency.

One complaint has already been lodged with Emily O'Reilly, the EU Ombudsman.

According to the Good Lobby, a non-profit organisation which is campaigning for what it calls the equalisation of access to power, one of its directors Alberto Alemmano, who is also Jean Monnet Professor of EU Law at the HEC international business school in Paris, has formally submitted a complaint.

Mr Alemmano claims the video is in breach of Articles 9 and 10 of the Commission's code of conduct, updated in 2018, because von der Leyen had delivered a political endorsement.

Article 9(3) of the code says that Commissioners "shall abstain from making public statements or interventions on behalf of any political party or organisation of the social partners of which they are members, except when standing for election/participating in an election campaign".

The article qualifies the prohibition by saying that "this is without prejudice to the right of [Commissioners] to express their personal opinions".

For now this remains the main defence of the von der Leyen team: that she made the contribution in her personal capacity and that the producers of the video had erroneously created the impression she was making it as Commission President.

However, Ms von der Leyen appeared to deliver the message in the same spot as she has delivered almost daily video messages on the Commission’s response to the coronavirus pandemic and delivered via Twitter.

Emily O'Reilly is already investigating a code of conduct complaint against the Croatian Commissioner Dubravka Šuica, who is also a vice-president, over her participation in a phone-in show on Croatian television.

The complaint against Ms Šuica was lodged by a Croatian citizen who felt that the Commissioner had verbally attacked a caller for criticising public figures.

Specifically, the complainant said the Commission’s response to what Ms Šuica had said had emphasised the importance of free speech, but had failed to address the allegation of a breach of the Commission’s code of conduct.

The Commission had written to the complainant that Ms Šuica had "reiterated her unwavering support for those freedoms [of expression and pluralism in the media] and clarified that it was not, and is not, her intention to impair the independence of the TV station in question".

On 29 June Ms O’Reilly wrote to von der Leyen confirming an investigation was, indeed, under way into the Croatian commissioner’s contribution to the TV show. 

"My inquiry team has reviewed a transcript of the Vice-President’s appearance in the call-in show and related reports in the Croatian media.

"Based on this transcript, Vice-President Šuica acknowledges that the caller 'has the right to his position', but also appears to say that she believes that the media should not broadcast or publish statements criticising public figures.

"She also seems to imply that the radio station allows such critical statements to be broadcast in order to increase its popularity."

Ms O’Reilly wrote she had previously recommended that European Commissioners be "mindful of the need to exercise due caution in media interviews".

She wrote: "Given the paramount importance of freedom of expression and the freedom and pluralism of the media, any statements that could be perceived as an attempt to stifle critical media coverage should be avoided".

Since this case also involves the code of conduct, which legally requires Commissioners to exercise discretion in their public utterances, it is understood Ms O'Reilly may decide to examine the two cases in parallel.

A spokesperson for the Ombudsman said a response to the complaint about von der Leyen's appearance on the HDZ video will be issued within days.

Von der Leyen has been admired for her sure-footedness during the Covid pandemic, and arguable steadied the EU ship after bitter allegations that member states were not helping each other out when the virus struck.

However, her appearance in the video has left some observers in Brussels surprised that she would leave herself open to accusations of political partisanship when her position as Commission President is supposed to be strictly neutral.

At a time when many Europeans have been aghast at Donald Trump’s relentless politicisation of the pandemic from the White House, this was a misstep President von der Leyen may well regret, especially if Emily O’Reilly does indeed launch an investigation.