French socialist woos Europe with new vision

He added that the European project could not only base itself on emblematic projects such as the Erasmus student exchange programme or industrial initiatives, "which start to feel a bit jaded".

Europe could not be saved, either, by talk of European values. "It's important, but not enough”, he said.

"We have to be much more ambitious," he said, adding that the "status quo of austerity and free trade will lead to the dislocation of Europe in the mid and long term".

Russia

"I don't see how the programmes that have profited the rise of far-right nationalism everywhere in Europe, that would scrap public services, roll back workers rights and the welfare state, would prevent us from one day having Marine Le Pen as the president of France, " he said, referring to the French anti-EU and far-right presidential contender.

In another jibe at his opponents, he said that France should take more refugees among Europe's "crisis of solidarity with migrants", and backed wider use of humanitarian visas.

He spoke at length about Russia, noting that three candidates in the French presidential race - Marine Le Pen, Francois Fillon, and Jean-Luc Melenchon - were in favour of recognising Russia's annexation of Crimea from Ukraine.

He said that could open up a number of old border disputes in Europe.

"We should discuss with Russia, but we have never stopped to do that. And in order to discuss with [Russian leader Vladimir] Putin, there is need to use some good arguments: international legitimacy, the right of a country to be sovereign over its territory,” Hamon said.

“The Minsk agreement has to be followed”, he said, referring to an EU-brokered pact that obliged Russia to stop its war in east Ukraine.

’Poor Moliere’

Hamon also attacked Fillon, the centre-right candidate, for his support for the so-called Moliere clause.

The Moliere clause is a rule imposed by some local governments in France which flies in the face of EU free movement by saying that construction workers on public projects must speak French for safety reasons.

Hamon's own socialist colleagues from Centre-Val de Loire, a French administrative region, have backed the rule.

But Hamon called it a discriminatory measure against Polish and other workers, and implored politicians to leave "poor Moliere" out of what he called a borderline racist measure.

"Better call it the Tartuffe clause,” he said, by reference to the charlatan hero of a Moliere plays.

Pro-European

Hamon's rally was backed up by Elio Di Rupo, the former socialist prime minister of Belgium, and Thomas Piketty, the French star economist whose book, Capital in the 21st Century, has sold more than 2.5 million copies worldwide.

Piketty told the audience he had teamed up with Hamon because of his views on Europe.

"Others say they are the European candidate, but Hamon is the only pro-European candidate," he said, referring to Hamon's liberal rival Emmanuel Macron.

The economist and his wife, the economist Julia Cage, have been working together with Hamon on a Treaty on the democratisation of the governance of the euro area, or "T-dem".

The 12-page pamphlet calls for the establishment of a parliamentary assembly for the eurozone, in which 80 percent of the seats are filled by national MPs and the remaining share by MEPs.

"This would give democratic legitimacy to eurozone governance and allow it to stop austerity policies in Europe," said Piketty.

He added that it was the most detailed proposal for Europe of any presidential candidate's campaign. He also said France was punching below its weight in the EU.

"France likes to complain, but it's more constructive to put a proposal on the table. It would be difficult for EU leaders to caricature that France is complaining, but lacks an alternative governance model for how to make Europe more social and democratic," he said, drawing applause.

German support

Hamon was the first of France's 11 presidential-hopeful to take his campaign to Brussels.

Earlier in the day, he met with the president of the European Commission, Jean-Claude Juncker; the commissioner for economic affairs, French socialist Pierre Moscovici; as well as left and Green euro-deputies.

Afterwards, he told journalists his proposals were not seen favourably by the EU executive.

Earlier in March, Moscovici wrote to Hamon to say that EU leaders would never back his proposals.

But the French socialist, who hails from the left-wing fringe of his party, suggested that this would be to his political advantage.

"I didn't make my proposals to please the commission," he said.

He was hopeful Germany could be convinced to support the proposal.

"I'm being told that the Germans don't want this, but Germany is not a homogeneous bloc. There is also an internal, democratic discussion within the country," Hamon said.

He said he would seek the endorsement of German socialist chief Martin Schulz, the former president of the European Parliament who was elected party leader of the German Social-Democratic Party (SPD)last Sunday.

Hamon said he "wasn't surprised" that the dethroned SDP leader Sigmar Gabriel had endorsed Macron, and hoped for better relations with Schulz.

"Schulz wants to construct a left-wing majority [in Europe],” he said.