BUCHAREST, Romania — Days after European elections emboldened nationalists in the heart of Europe, Pope Francis arrived on Friday in Romania, on the Catholic and European periphery, to appeal for unity and assert himself as the global conscience on the dangers of populism.

In his three-day trip to the former communist country, now a staunchly pro-European member state, the pope will try to heal an ancient schism between the Catholic and Orthodox churches.

But he reminded the Continent of its common values and lent support to Romanian emigrants and a Roma ethnic minority that, in some countries, has again become a target of right-wing vitriol.

“To move forward together, as a way of shaping the future, requires a noble willingness to sacrifice something of one’s own vision or best interest for the sake of a greater project,” said Francis in the first papal visit to Romania since John Paul II came here 20 years ago. Addressing the country’s leaders, he added that cooperation “makes it possible to advance securely toward shared goals.”