French President Emmanuel Macron has warned that "there seems to be a European civil war" between liberal democracy and rising authoritarianism.
He urged the EU to renew its commitment to democracy, in a passionate speech to the European Parliament in Strasbourg.
"I don't want to belong to a generation of sleepwalkers that has forgotten its own past", he said, recalling how the EU arose after World War Two.
He is launching debates with voters, aimed at re-engaging them with the EU.
In his speech he condemned what he called "a fascination with the illiberal" in Europe.
Last year Mr Macron and his new liberal party, La République en Marche (LREM), triumphed in French elections with a strongly pro-EU platform.
His second-round rival in the presidential election was National Front (FN) leader Marine Le Pen, a nationalist and fierce critic of the EU.
Mr Macron was also hitting back at the Eurosceptics who drove the vote for Brexit in the UK.
As Brexit will leave a big hole in the EU budget he said there should no longer be budget rebates for some member states. He added that France was prepared to increase its contribution.
Mr Macron's set-piece speech in Strasbourg set out his vision for democratic renewal in the EU, at a time of growing nationalism in the 28-nation bloc.
This month Hungary's right-wing leader Viktor Orban, another arch-critic of EU policies, won a new two-thirds majority in parliament.
There is much nervousness in the EU about Russian influence on European voters, with many examples of fake news spreading in social media - often blamed on supporters of Russian President Vladimir Putin.
MEPs applauded Mr Macron when he said democracy "is a word with meaning, which emerged from the battles of the past".
He faces a big challenge ahead of the 2019 European elections as his LREM party does not belong to any of the main groups in the European Parliament.
By Adam Fleming, BBC News, Strasbourg
President Macron used some memorable phrases as he sought to reinvigorate European democracy.
The divisions in Europe were like a "civil war… where there is an increasing fascination with illiberalism".
And was he referring to Brexit when he said that, in response to problems, some proposed a yellow brick road, to take their people off on an adventure somewhere else?
There was some policy amongst the poetry - support for a temporary digital tax that could become permanent, a new fund for communities that take in migrants, copyright laws to protect European culture, and a call for a roadmap for eurozone reforms, which are controversial in Germany and northern Europe.
Most striking was his heralding of a new generation that didn't experience World War Two and saw Europe in a different way. But will next year's elections for the European Parliament usher in a wave of MEPs who want to strengthen the EU, or to rip it apart? That's the test.
Mr Macron identified some key areas of "European" - rather than national - sovereignty: tackling climate change and environmental problems; health; minority rights and privacy.
He wants France and Germany to be in the vanguard of ambitious eurozone reforms, including turning the bailout fund - the European Stability Mechanism (ESM) - into a European Monetary Fund, like the IMF.
The idea is that an "EMF" could tackle a country's debt problems and other financial crises before they spread to the rest of Europe.
However, German Chancellor Angela Merkel's Christian Democrats are wary of any scheme that could make richer countries liable for the debts of poorer partners.
In a debate with MEPs after his speech Mr Macron said he wanted to keep the UK close to the EU despite Brexit, but "there's no cherry-picking in the single market".
He said there must be "full respect" for the freedoms of the EU single market: free movement of goods, services, capital and people.