France's Pierre Moscovici struggled to convince European Union lawmakers today that he could enforce budget rules that his own country has repeatedly breached, as the formation of a new European Commission turned into a bitter political battle.

The Socialist, who was finance minister in Paris until six months ago, promised to apply the bloc’s deficit rules equally to all euro zone states, including his own, if confirmed as economic and monetary affairs commissioner.

But he faced a barrage of scepticism from conservative lawmakers who asked how he could credibly recommend reforms and cuts to ministers that he had not implemented himself in Paris.

"Budgetary rules have to be respected, and respected by all member states, without being harder on some more than others," Moscovici told a European Parliament confirmation hearing. "You can count on me to be a fair and impartial arbiter."

But he also said budget deficits could not be cut without economic growth, and he would use all the flexibility available in the EU’s rulebook to promote investment, growth and jobs.

His torrid interrogation came a day after France defied its partners by unveiling a 2015 budget that will again miss EU targets, saying it would need two more years – on top of a two-year delay already granted – to bring its deficit below the treaty limit of 3 percent of national output.

Moscovici drew some gasps of astonishment when he said Paris had never broken the rules, since each of its budgets had been approved in advance and in execution by the EU authorities.

"It took Germany 10 years to change from the sick man of Europe to the strongest economy. France also needs time," he said. He added that the time was not ripe for Eurobonds, jointly issued debt by euro zone countries, and it was unlikely to be on the agenda in the incoming EU executive's five-year term.

Dutch conservative Esther de Lange asked whether he would be “an Animal Farm commissioner in which some countries are more equal than others”. Her Austrian colleague, Othmar Karas, spoke of a “credibility gap” between what Moscovici said he would do now and what he could have done but had not done at home.

The tough questioning appeared to be partly retaliation for the rough ride that left-wing and Greens lawmakers gave on Wednesday to the Spanish conservative nominee for EU energy and climate action chief, Miguel Arias Canete, over his family links to the oil industry.

The left and Greens also forced the British nominee for financial services commissioner, Jonathan Hill, to resit his examination next week after he stumbled over detailed questions on Eurobonds, high frequency trading, shadow banking and his plans for a proposed EU capital markets union.

Centre-right lawmakers were out for revenge and the French Socialist was an obvious target given Paris’ budget woes.

“Moscovici . . . will have a very hard time,” Peter Liese, a German centre-right lawmaker, said before the hearing, fuming at the treatment of Arias Canete, whom opponents on the environment committee said was disqualified both on grounds of conflict of interest and due to his past policy views.

“From today, it’s very clear we will be much tougher. We were so kind with the other political groups until now.”

Claude Turmes, a Green from Luxembourg, spoke of a "dirty game behind the scenes" in which the right was blocking a committee vote that could kill off Arias Canete's candidacy and threatening to block the high-profile appointment of Moscovici.

Incoming European Commission President Jean-Claude Juncker had hoped a broad understanding between his centre-right and the mainstream left could secure swift passage of a team he says can revive the economy and win back voters who returned a phalanx of anti-EU parties to the parliament in May.

But many lawmakers are also keen to demonstrate their independence from the Commission, and from the 28 governments of the Union, each of which nominates one member to the executive.

After the approval of the first 10 of the nominees in the first two days of hearings, angry scenes in parliamentary committee rooms on Wednesday night threatened to disrupt a timetable under which the new Commission is supposed to be approved en bloc on October 22nd and to take office on November 1st.

Any delay could draw leaders of European governments into the dispute and might, if prolonged, leave the outgoing team of Jose Manuel Barroso as a lame duck handling the confrontation with Russia over Ukraine, trade negotiations with Washington and rumbling divisions over austerity and deficits in the euro zone.

Juncker, a long-time prime minister of Luxembourg and veteran EU dealmaker, has made a point of startling choices, naming figures to roles in which they or their governments have been at odds with Brussels. Some have described it as turning poachers into gamekeepers.

But the strategy could backfire if lawmakers cannot be convinced to trust a Briton to oversee EU banking, a French Socialist to enforce budget discipline or a Hungarian right-winger to uphold human rights and media pluralism.

Hill seemed to charm many of his interrogators with wit and warm words for European integration that set him apart from Eurosceptics in his party. But he failed to convince critics he was on top of a brief that would give a Briton a big say over the euro zone, to which London wants access for its financial services industry but refuses to join by using the EU currency.

Hill assured them he was “not here as a representative of the City of London”, promised to act in the common EU interest, praised his French predecessor and flattered the legislature.

In a possible olive branch, the centre-left Socialist group praised his personal qualities and communications skills and kept the door open to approving him next week if he provides more specific answers on policy issues.

“We believe that he can be a good commissioner but he did not entirely convince us in relation to the content and priorities of his portfolio,” Socialist lawmaker Elisa Ferreira said in a statement.

In another hearing, Hungarian nominee Tibor Navracsics had to rebuff questions on his role in a Budapest government that has clashed with the EU over its treatment of minorities and laws that Brussels says restricted the media and free speech.

Seeking the education, culture and citizenship portfolio, he highlighted his role in negotiating Hungary’s modification of new laws under EU pressure and his embrace, having grown up under communist dictatorship, of European values of democracy.

It was not clear what the next steps on Arias Canete and Navracsics’s candidacies would be. One EU official said Juncker did not expect more parliamentary decisions until Monday.