By Angelo Amante and Gavin Jones

ROME (Reuters) -Italian Prime Minister Giorgia Meloni's decision not to back Ursula von der Leyen as European Commission chief was driven by fear of losing rightwing grassroots supporters, analysts say, but may curb her influence over EU choices.

The European Parliament elected von der Leyen for a second five-year term on Thursday to lead the bloc's executive with support from centre-right, centre-left, liberal and green groups. She got 401 votes, far above the 361 needed.

Meloni's Brothers of Italy, part of the European Conservatives and Reformists group (ECR), revealed its decision after the vote when it said von der Leyen had shifted too far left, particularly on green pledges.

Even though von der Leyen did not need Meloni's 24 lawmakers to win, the vote marked a shift from the prime minister's past efforts to keep good relations with the Commission as Rome grapples with mammoth public debt.

"Meloni cares a lot about being consistent. She had said she would never vote with the left. When it became clear that her votes were not needed, she stuck to that pledge," said Giovanni Orsina, politics professor at Rome's Luiss university.

However, the move dismayed many Italian commentators who said the Commission may now be less indulgent towards Italy's public finances and its faltering attempts to spend billions of euros of EU post-COVID recovery funds.

That remains to be seen, but Meloni's first concern appeared to be fending off internal competition at home from her hard-right coalition ally, Matteo Salvini's League.

"She is afraid of exposing herself on the right, and this fear overwhelmed everything else," said Francesco Galietti, from Rome-based political risk consultancy Policy Sonar.

CORE VOTERS

Brothers of Italy is now polling at nearly 30% - its highest ever - while the League is around 8.5%, but Galietti pointed to volatility in Italian politics and said Meloni could not afford to alienate traditional voters.

Before moderating her positions after coming to power in 2022, Meloni was considered further to the right than Salvini, and used to advocate for Italy to leave the euro zone.

The Commission declined to comment for this story.

Von der Leyen, asked by reporters on Thursday whether she regretted seeking Meloni's support, said only that the vote showed she had taken the right approach in assembling backers who are "pro-European, pro-Ukraine and pro-rule of law."

Carlo Calenda, leader of centrist party Action, said in a radio interview on Friday that Meloni had preferred to be "a faction leader rather than a prime minister," and it was "dangerous" for Italy to be in opposition in Europe.

Meloni triumphed in Italy's European Parliament elections last month, in contrast to setbacks for French President Emmanuel Macron and German Chancellor Olaf Scholz, but since then things have not gone her way.

After being left out of a deal on the bloc's top jobs she protested that von der Leyen and other leaders were flouting voters' wishes by ignoring a surge in right-wing support.

She refused to back von der Leyen along with groups including the Patriots for Europe, a far-right alliance which includes Marine Le Pen's French National Rally (RN) and Hungarian Prime Minister Viktor Orban's Fidesz.

LESS WEIGHT IN EUROPE?

Some analysts are suggesting Meloni did not want to side with the EU's mainstream forces ahead of a possible Donald Trump victory at U.S. elections in November that could boost the bloc's nationalists.

Yet Wolfango Piccoli of London-based political risk consultancy Teneo, said such a strategy could backfire as Trump would likely embrace an isolationist foreign policy which would oblige Italy to strengthen European bonds.

"A plan like that would not be useful to the Italian national interest," Piccoli said.

In an interview with Italian daily Corriere della Sera published on Saturday, Meloni said she would still be able to work with von der Leyen and that it would be "surreal" to imagine Brussels would punish Italy when it came to deciding on Commission roles. Rome's candidate is European Affairs Minister Raffaele Fitto.

But her relationship with Brussels looks trickier now and Piccoli said it might be harder to have a say on issues including defence and migration, though budget procedures based on pre-established steps are less likely to be affected.

"The real question is to count in Europe," he said.

(Reporting by Angelo Amante and Gavin Jones; Editing by Andrew Cawthorne)