PARIS, April 14 (Reuters) - U.S. officials who met leaders of France's far-right National Rally were underwhelmed by their economic plans, two diplomatic sources said, in a blow to the party's efforts to present itself as a credible steward of the euro zone's No. 2 economy before next year's election.

The National Rally has become France's largest parliamentary party - and a potential victor in 2027 - by coupling a hardline stance on immigration with populist pledges to defend jobs and purchasing power. But its longstanding rhetoric around state interventionism and protectionist policies worries French blue-chips and investors.

U.S. Ambassador Charles Kushner and his team have met with most of the likely presidential contenders from across France's political spectrum, including National Rally (RN) party chiefs Marine Le Pen and 30-year-old protege Jordan Bardella.

While they were not particularly swayed by any of the candidates they met, the RN's views on how to cut a yawning deficit, win U.S. investment and get the economy moving were a concern, the sources said.

Reuters granted the sources anonymity to allow them to speak frankly about private discussions.

Their conclusion echoed concerns among many in France's business elite nL8N3YY1W3 about whether the RN has the experience or expertise to steer the highly indebted $3.5 trillion economy back to robust growth and steady the country's public finances.

The RN did not respond to a request for comment on the U.S. officials' view. A senior aide to Bardella said the party was working to develop its economic programme, including politically sensitive structural reforms to France's costly pension system.

A State Department spokesperson declined to comment on "private diplomatic exchanges".

ELECTION HEADACHE 

Doubts over the RN's economic programme may pose an electoral hurdle in France and shape U.S. thinking on whether to vocally support the RN in 2027, when polls suggest it could win.

U.S. President Donald Trump's administration has backed ideological allies nL1N40Q06M in Europe, but with mixed results. A U.S. push to help Hungarian Prime Minister Viktor Orban win re-election backfired when he lost power nL8N40V07J after 16 years on Sunday.

One of the diplomatic sources said there were no signs RN leaders were seeking U.S. support, and European far-right and populist parties that once cheered Trump are increasingly wary nL8N3YM0QR of being seen as too close.

France's economy is mired in a morass of feeble growth, high borrowing costs and a debt burden that is one of Europe's heftiest at 115.6% of GDP. 

The RN says its economic priorities include boosting household purchasing power through tax cuts, reducing public spending and France's EU budget contribution, and restructuring welfare to prioritise French citizens. 

But detailed plans have yet to emerge. Critics say the party lacks a coherent economic manifesto.

U.S. officials were concerned by a combination of mixed messaging on the economy, including the RN's desire for a costly rollback of a 2023 pension reform that raised the retirement age, and unclear plans on how to trim the deficit, the sources said.

They were also irked that the RN voted in favour of a budget amendment doubling to 6% a digital services tax that Washington opposes on the grounds it targets U.S. tech giants, the sources added. The amendment never made it to the final 2026 budget. 

RN'S LE PEN MET CEOS

Business leaders earlier this year told Reuters they were confused by the divergent economic currents within the party leadership, with Le Pen seen as a big-spending populist, and Bardella seeking to chart a more pro-business path. 

That ambiguity initially helped the RN broaden its support, but has become a liability as the party seeks to present itself as a credible government-in-waiting, executives say. 

Despite making headway with voters, the RN, a party long-shunned by France's political and economic elites, has been struggling to make headway with France Inc nL8N3YY1W3. 

But in a sign CEOs want to understand the party's economic programme as the April 2027 election edges closer, Le Pen met with the bosses of luxury group LVMH, oil major TotalEnergies, insurer AXA and Renault among others on April 7, two other officials said.

Fund manager François Durvye, whom Bardella brought on as an economic adviser, helped facilitate the meeting, one official said. The same official summarised the meeting as a heated Q&A session.

The second official, a senior figure in the RN, said the meeting was designed to dispel "the caricatures that are often painted of our programme, which is in fact the most pro-growth and pro-business programme across the political spectrum."

(Additional reporting by Elizabeth Pineau and Mathieu Rosemain; Editing by Richard Lough and Andrew Heavens)