German Chancellor Angela Merkel said nationalism remains the key threat to the global order, setting herself up as President Donald Trump's main adversary in Europe for another year.

Signaling she intends to use her clout even as a lame-duck leader, Merkel evoked the horror of Europe's 20th-century wars in her New Year's Eve address while calling for Europe to stand together in 2019 as the United Kingdom heads toward the exit consumed by domestic political battles and populists seek gains in an E.U.-wide election.

Climate change, migration and terrorism are global challenges best addressed "when we take the interests of others into account," Merkel said in an advance copy of her speech broadcast on Sunday evening.

"That is the lesson of two world wars last century," she said. "Today, that conviction is no longer shared by all. Certainties of international cooperation are coming under pressure. In such a situation, we have to advocate, argue and fight for our convictions more strongly."

Her comments reflect her determination to keep using the power of her office to shape the political agenda after a year of waning authority in which she agreed to step aside as chancellor by 2021 and gave up the leadership of her Christian Democratic Union.

Pressed by the U.S. on trans-Atlantic trade, a Russian gas pipeline and business with Iran, Merkel also faced electoral setbacks for the CDU amid a continuing backlash against her open-borders refugee policy that's been derided by Trump.

While there's growing speculation about her staying power after 13 years in office and Merkel, 64, offered a de-facto apology for her government's performance, she made it clear that she isn't ditching convictions that have led some to champion her as the world's defender of liberal democracy — a label she resists.

"We are committed to a more robust, more decisive European Union," Merkel said. In May, voters in the European Parliament election can help ensure that "the European Union will remain a project of peace, prosperity and security," she said.