ROME (AP) — Worried about anti-European Union sentiment fueling nationalism on the continent, a top official said Thursday that the bloc must "stop the radicals" from gaining power by making citizens feel safe amid the migrant crisis.

EU Council President Tusk joined other leaders in a debate in Rome on the state of the European Union.

Nationalists and anti-European sentiment have gained ground in elections in several EU nations. Fears of being overwhelmed by migrants are testing a major EU accomplishment — Schengen "border-free" travel — as several countries erect or plan physical barriers.

"Today we have to admit that this dream of one European state with one common interest, with one vision...one European nation, this was an illusion," Tusk said.

The former Polish prime minister said the EU is facing a "really risky and tricky" moment.

An urgent goal for Brussels, Tusk said, must be to "convince our citizens that we are able to provide this feeling of security and stability" by "re-establishing effective control of our external borders."

That strategy, Tusk contended, can "stop the radicals in their march for power."

Much of the EU's external sea borders is being sorely tested by human traffickers who launch unseaworthy boats filled with migrants toward Italian, Greek and other southern nations from Libyan shores. Hundreds of thousands of refugees have been brought to EU shores when rescued at sea and then seek asylum in EU nations.

European Commission President Jean-Claude Juncker, citing the migrant crisis, said "suddenly we discovered that not everyone was applauding or sharing" EU views.

The EU officials came to Rome on the eve of a ceremony at the Vatican to give Pope Francis the International Charlemagne Prize for his message of tolerance, solidarity and encouragement. The prize honors work done in the service of European unification.