BRUSSELS — European leaders on Tuesday proposed awarding the powerful presidency of the European Commission to German Defense Minister Ursula von der Leyen, putting a forceful advocate of transatlantic ties into the job at a time of international uncertainty.

The European Parliament needs to give final approval — not a sure bet — but, if confirmed, von der Leyen, an ally of German Chancellor Angela Merkel, would be the first woman to fill the European Union’s top post.

European leaders also nominated International Monetary Fund Director Christine Lagarde to helm the European Central Bank, a decision that would give that institution, too, its first female head. Belgian Prime Minister Charles Michel was tapped as the next president of the European Council. And Spanish Foreign Minister Josep Borrell would be charged with supervising the struggling Iran nuclear agreement as the E.U.’s foreign policy chief. 

Those decisions came after weeks of negotiations. Wrangling over the E.U.’s senior posts is always complex, but this year’s maneuvering reflected an increasingly divided Europe. The talks broke the record for length of an E.U. summit. They included one marathon session that began Sunday evening and continued until Monday afternoon. And discussions continued even after the European Parliament began its new five-year session on Tuesday.

“We believe that this is a good group of people that we have nominated,” Merkel told reporters after the announcement. “It is a good thing that for the very first time a woman is going to hold that. I welcome that, irrespective of any country or party considerations on my part.”

Von der Leyen, 60, has emerged as a tough advocate for Germany and NATO in her years as defense minister. At home, she has pushed for more defense spending, a major focus of dispute with the United States. Abroad, she has cheered the value of diplomacy and multilateralism in an implicit rebuke to President Trump

But she has also come under fire for the woeful state of the German military, which suffers from years of underinvestment and neglect. Many helicopters can’t fly. Many tanks don’t drive.

The European Commission is the executive arm of the European Union, a 32,000-employee-strong juggernaut charged with writing E.U. regulations and enforcing them. Its reach is global: The digital privacy laws that it wrote have forced changes by U.S. tech companies. Its antitrust enforcement is often more aggressive than in the United States. And, in concert with European leaders, it has tried to push an ambitious plan to fight climate change.

As its head, von der Leyen would be empowered to strike trade deals on behalf of the 500 million E.U. citizens, negotiate Brexit and propose and enforce Europe’s powerful regulations. Although many European citizens don’t understand the details of the job, its influence touches all parts of their lives. 

Von der Leyen would also be charged with taking on President Trump.

When she has delivered her broad vision for world order, she has hit at Trump’s approach to diplomacy and his deference to Russian President Vladi­mir Putin.

“There can be no policy of equidistance between allies on one side and those who on the other question our borders, our values and the principles of ­international law,” von der Leyen said in Munich in 2017, shortly after Trump came to office.

French President Emmanuel Macron said von der Leyen would figure out a working relationship with the U.S. leader.

“She will do what it takes to have a great relationship with the U.S., to serve European interests and to avoid useless conflicts,” he told reporters.

Von der Leyen is deeply familiar with Brussels. The daughter of an E.U. civil servant, she was born and lived here until she was 13. She speaks native-level French along with German and English. She is a doctor who lived for four years in California in the 1990s. She also has seven children. A senior member of Germany’s center-right Christian Democrats, she is the only person to have served as a minister during the entirety of Merkel’s 14 years in office.

If confirmed, she would replace Jean-Claude Juncker, 64, a former Luxembourg prime minister, who has served as European Commission president since 2014.

The continent’s center-right bloc has held the presidencies of the European Commission, Council and Parliament in recent years. This time around, though, an initial lead candidate for Commission president, Manfred Weber, failed to command support among the leaders of the E.U.’s 28 countries. He had never held office outside the European Parliament, and some leaders felt his résumé was too slim for the position. 

A second nominee, Dutch Social Democrat Frans Timmermans, had gained enemies after confronting the leaders of Hungary, Poland and Romania with concerns about the health of their democracies.

Some leaders also said they wanted more women represented in the highest ranks of the E.U.

Critics — including some of the European Parliament party chieftains whose support may be necessary to win backing for the deal — said E.U. leaders were undermining democracy by awarding the posts to candidates who had not put their names forward publicly during May’s elections for European Parliament. Others said that it set a bad precedent for central European countries that had tangled with Timmermans on rule-of-law issues to be able to veto him. It remains possible that the European legislature could torpedo the decision and force a new start.

But national leaders backed the slate unanimously. Only Germany abstained, the result of internal disagreement from the Social Democrats, Merkel’s coalition partners.

“The fact that she’s Merkel’s choice gives her a lot more credibility and political support than a lot of candidates that were mentioned,” said Heather Grabbe, head of the Open Society European Policy Institute.

Birnbaum reported from Athens.