By William Horobin 

PARIS--When France's Pierre Moscovici took to social network Twitter to deny he fell asleep during a euro crisis meeting in 2013, he slammed the reports as "French bashing."

As the former finance minister vies to become a top economic commissioner for Europe--and tries to convince doubters a Frenchman is up to the job of policing European budgets--he says he's plagued by the same bias.

"We have to stop with facile French bashing," Mr. Moscovici said in an interview. "France is a serious country that people can have confidence in and a French commissioner, whatever the portfolio, is a commissioner people can have confidence in."

The 56-year old Socialist has become a key piece in a complex game that has European capitals and political parties wrangling for influence in the renewal of the European Commission, the EU's executive arm, in the fall

At the heart of the negotiations are German and northern European concerns over a French official taking over budget-policing after France repeatedly missed targets for bringing down its own deficit, including under Mr. Moscovici's watch as finance minister.

"One aspect is of course how the public, and not just in France but in all of Europe, would react if such a post if such a situation were filled with a French candidate of all things," German Finance Minister Wolfgang Schäuble said in a radio interview last week.

The tensions underscore a lingering division over economic policy between the euro zone's two largest economies.

As France struggles to recover from years of weak economic growth and rising unemployment, officials in Paris have pointed to the weight imposed by German-inspired austerity on the region over the last five years. Berlin, meanwhile, is reluctant to relinquish a tight hold on budgets and argues that doing so would undermine confidence, further harming the tepid economic recovery in the euro zone.

German officials have welcomed the French government's recent plans for tax cuts to help businesses recover from the crisis, but stress that is not a reason to soften rules to give France yet more time to meet fiscal goals. "Time in itself doesn't create confidence," said Mr. Schäuble.

As the finance minister who negotiated with European Union authorities to get a two year delay to 2015 to bring France's deficit within the EU rule of 3% of economic output, Mr. Moscovici has become a lightning rod for the debate over a possible shift in policy.

"A Moscovici appointment is symbolically and substantially significant," said Mujtaba Rahman, euro-zone analyst at political risk research firm Eurasia Group. "We are looking at a world where France is set to get some more flexibility and certainly a reinterpretation of the rules."

Europe's left-leaning bloc of governments are pushing for a socialist to get the top economic post at the EU's executive to counterbalance Luxembourg's former prime minister Jean-Claude Juncker, a center-right politician who has already secured the commission presidency. French President François Hollande wants to seize on the reshuffle to prioritize economic growth and limit austerity by using all the possible flexibility on budget rules.

"From the moment France wishes to change the direction of Europe toward growth and jobs, France is justified in asking for an economic portfolio, " Mr. Moscovici said.

In recent weeks, German officials have been vocal in opposing that logic. The debate became heated when Norbert Barthle--a senior lawmaker in Angela Merkel's CDU party--likened appointing a French candidate to the top economy job to "casting out devils with Beelzebub."

Mr. Schäuble stepped in to say Mr. Moscovici, with whom he has a close working relationship, was a very good finance minister and German criticism doesn't apply to him directly. But he still expressed reservations about the message that the nomination of a French candidate would send. In a bid to further calm tensions, Mr. Schäuble has tried to push the debate behind closed doors.

"These kinds of decision are very sensitive. The more we talk about it, the more difficult it becomes to make a decision," Mr. Schäuble said earlier this week in a joint newspaper interview with France's current finance minister Michel Sapin.

Mr. Moscovici played down the conflict with Germany and said he never broke fiscal rules because the two year extension he negotiated for Mr. Hollande to meet deficit targets is in line with the flexibility of EU treaties.

"There is no antagonism between France and Germany. Germany wants a strong France and the Germans have approved our policies over the last two years," Mr. Moscovici said.

Mr. Moscovici, who as finance minister repeatedly pushed back at what he perceived as a bias against France, is yet to be designated as France's official candidate. But when he left the French government in April, Mr. Hollande charged him with a report into how European policies can boost jobs and growth to prepare Mr. Moscovici for a role in Europe.

"If I am commissioner, I will be a Frenchman, and a member of the European Commission, and also a politician with beliefs that remain social-democratic," Mr. Moscovici said.

Andrea Thomas in Berlin contributed to this item.

Write to William Horobin at William.Horobin@wsj.com