The conservative European People's Party (EPP) -- the biggest force in the EU parliament -- is expected on Thursday to formally support European Commission chief Ursula von der Leyen's bid for a second term.

Having navigated multiple crises ranging from Covid to the Ukraine war as the European Commission head since 2019, the former defence minister is seeking a new mandate that would run to 2029.

The backing of the EPP would be key for the 65-year-old German, who needs to get the endorsement of the EU parliament to be re-named to her post.

Some 1,500 EPP representatives -- including lawmakers, party leaders and 12 heads of state and government -- are attending the party congress.

"Our peaceful and united Europe is being challenged like never before. By populists, by nationalists, by demagogues. Whether it's the far right or it's the far left," von der Leyen said in her speech at the congress in Bucharest.

"They want to trample on our values, and they want to destroy our Europe. And we, the EPP, will never let that happen," she added.

During the conference's opening day Wednesday, EPP leader Manfred Weber hailed von der Leyen as a "solid leader", who could count on the support of a vast majority of members, adding that Europe would be "in good hands" with her at the helm.

The result of the secret ballot in the Romanian capital is expected to be announced at around 12:30 pm (1030 GMT).

- 'Broad support' -

As the largest grouping in the parliament, the EPP is keen to put on a show of strength ahead of the European elections.

Romanian President Klaus Iohannis is leading the meeting, also attended by Polish Prime Minister Donald Tusk, his Greek and Swedish counterparts Kyriakos Mitsotakis and Ulf Kristersson, and European Parliament President Roberta Metsola.

Scheduled to take place from June 6-9, the European elections will reshuffle the political balance in Brussels, including at the Commission.

Within the EPP, von der Leyen -- the first woman to hold the top EU post -- "enjoys broad support and her (policy) record gives her a positive image," said Thierry Chopin, special adviser at the Jacques Delors Institute.

But she has come under fire in recent years, particularly from France's liberal conservatives who have denounced "a form of technocratic drift that is harming our farmers".

Von der Leyen's flagship achievement in her first term -- the European "Green Deal" -- is turning politically toxic, with farmers mobilising across Europe.

Faced with growing discontent and far-right parties riding high in polls, von der Leyen has relegated climate concerns to the backburner since announcing her bid a few weeks ago.

- 'It is us who decides' -

In another shift, the EPP called for asylum-seekers to be moved to "safe third countries" to assess their claims in its manifesto adopted at the congress on Wednesday.

Von der Leyen appears to be "looking for votes further to the right", said Chopin, in particular by moving closer to Italian Prime Minister Giorgia Meloni, with whom she recently travelled to Kyiv.

Having secured a narrow backing of just nine extra votes at the European Parliament in 2019, "she knows that she must gather as many votes as possible to ensure a majority," he stressed.

Von der Leyen on Thursday insisted that while continuing to fulfill "international obligations.... it is us, the Europeans, who decide who comes to Europe and under what circumstances, and not the organised crime (gangs) of smugglers and traffickers".

At their gathering in Rome over the weekend, Europe's Socialists (PES) -- the second-largest force in the European Parliament -- underlined the "importance" of the June elections ahead of expected surging support for right-wing groups.