LISBON — European Socialists will need to adapt if they don't want to "become obsolete," European Commission First Vice President Frans Timmermans told a party congress in Lisbon on Saturday after clinching the nomination to be their lead candidate in next year's European Parliament election.

Timmermans' nomination as the European Socialists' Spitzenkandidat was a formality after fellow Commission Vice President Maroš Šefčovič, the only other contender, pulled out of the race last month. The nomination makes the Dutch former foreign minister the Socialists' official candidate to be the next European Commission president.

"The world is changing so fast that if we don’t change with the world, we will become unnecessary to our citizens," Timmermans declared in his speech at the party's annual congress, in which he said that Europe had to respond to the "pressures" of a fourth industrial revolution. "You either adapt or you become obsolete."

Timmermans was nominated by acclamation after being presented to the congress by Portuguese Prime Minister António Costa as the party's candidate to end the center-right European People's Party's rule over the three main EU institutions.

Timmermans gave an earnest speech that contrasted with Costa’s address, which was televised live in Portugal. Drawing on his own record, he declared that socialists could grow the economy, boost the labor market, and still cut the deficit.

"It is quite surprising to see a prime minister operating a diplomatic taxi service for convicted criminals” — Frans Timmermans

Timmermans announced in October at a favorite café in the Dutch town of Heerlen that he would run to be the Socialists' candidate for the Commission presidency.

In Brussels, Timmermans is known for taking the lead on issues such as pursuing the Commission's dispute with the Polish government over the rule of law and cutting a migration deal with Turkey. He is popular within the party, though some, including French socialists, consider him too liberal for their taste.

In Lisbon, the 3oo-plus delegates seemed happy with the choice of lead candidate, despite not getting much of a direct say in the matter. They applauded particularly when Timmermans spoke about what he said were core issues of his campaign such as the fight against inequality and for the rule of law.

Timmermans took particular aim at Hungarian leader Viktor Orbán, saying that “it is quite surprising to see a prime minister operating a diplomatic taxi service for convicted criminals” — a dig at Budapest's decision to offer asylum to former Macedonian premier Nikola Gruevski.

Timmermans also used his party conference speech to address Brexit, an event he called "unspeakably sad." The U.K., he said, "is always more than welcome to stay part of the family," just days before British MPs are expected to vote on Prime Minister Theresa May's Brexit deal.

Timmermans also called for a "new social contract" and better parental leave policy, described tax competition as a "thing of the past," and chastized U.S. President Donald Trump for believing "a divided Europe is an American interest."

Other leading party members used the occasion to make pleas to revive socialist fortunes after significant electoral setbacks across Europe.

The Progressive Alliance of Socialists and Democrats — the European Parliament group of the Party of European Socialists (PES), which is home to 33 socialist parties — is on course to win only 142 seats out of 705 in the next European Parliament, on the back of just 20 percent of the EU-wide vote.

At the Lisbon congress, Spanish Prime Minister Pedro Sánchez was among those rallying party members.

"Social democracy has it hard," Sánchez said. "But I ask you: When has it been easy?"

Maltese Prime Minister Joseph Muscat also called on socialists to embrace change. "The answer doesn't lie in us being the defenders of the status quo," he said. "We have to be the Spotify, not the Walkman, of politics."

Florian Eder contributed reporting.