It’s official: António Guterres, former socialist prime minister of Portugal, will be the next secretary general of the United Nations.

Guterres had been the rumored frontrunner for months, but the selection still came as a bit of a surprise because many UN diplomats and observers believed that Moscow would only accept a candidate from Eastern Europe. (The current UN head, Ban Ki-moon, comes from South Korea; Ban’s predecessor, Kofi Annan, was from Ghana.)

In the end, Guterres, a consummate UN insider, easily beat out other top contenders like Argentinian Foreign Minister Susana Malcorra and former New Zealand Prime Minister Helen Clark, either of whom would have been the first woman to lead the world body.

Guterres’s victory was hailed by UN watchers, who describe Guterres in glowing terms. Formerly the UN high commissioner on refugees, Guterres is well-liked, with a reputation for being eloquent and outspoken on human rights. He also has a history of challenging powerful countries to do more to help the vulnerable rather than deferring to them. It’s a bold choice for an organization better known for making the safe one.

Now that the internal politicking is done, the big questions become: Who is Guterres? What does his selection mean for a UN beset by peacekeeping scandals abroad and a failed effort to stop the carnage in Syria? And how much can a secretary general — no matter how skilled — actually accomplish?

The last question may be the most important one. The UN secretary general wields no armies and controls no economies. And Guterres is coming into office at a time when two major powers, the US and Russia, are sharply at odds over the world’s most pressing crisis — Syria. It’s a hell of way to start his term.

Who is Guterres, anyway?

Guterres, who has a background as an academic, has been a politician nearly his entire life. In 1974, Portugal’s fascist dictatorship was toppled in a coup and replaced by a democracy. Guterres helped organize the Socialist Party, which soon emerged as the country’s main center-left faction.

In 1995, the Socialist Party won Portugal’s national election; Guterres, the party’s leader, became prime minister. At the time, Portugal was facing a fairly alarming rise in the rate of heroin addiction. Guterres’s response was to push through an unprecedented law decriminalizing the use of all drugs.

It turned out to be fairly successful. Portugal’s drug addiction rate is five times lower than the EU average, per Vice; the number of new HIV infections per year has fallen by 95 percent since decriminalization came into effect. It’s hard to say, for reasons my colleague German Lopez explains, that decriminalization was responsible for all of these benefits. But at the very least, it shows that decriminalizing drugs didn’t have any major negative effects on Portugal.

During his time in office, Guterres developed a sterling reputation among Portuguese politicians. Even his political opponents in Portugal’s center-right Social Democratic party respected him.

“I left the country 11 years ago, but I have a very vivid memory of how strong his reputation was,” André Corrêa d'Almeida, an adjunct associate professor of political economy at Columbia University who has written about Guterres, told me.

The secretary general is supposed to speak for the world, but the world rarely wants to speak with one voice

Guterres resigned from office in 2002, after the Socialist Party did poorly in local elections. He then turned to international politics. For a time, he led Socialist International, the global organization of social democratic parties, and in 2005 became the UN high commissioner for refugees, putting him in charge of its semi-autonomous agency tasked with assisting those fleeing wars, famines, and other forms of manmade and natural disasters.

Guterres earned plaudits in his new post, as well.

“He consistently positioned himself as the voice of world refugees; a sort of moral center who would put his own career prospects on the line by calling out powerful countries,” Mark Leon Goldberg, a journalist at UN Dispatch who covers the world body closely, writes.

Goldberg continues:

A couple years ago at an event at the United States Institute for Peace in Washington, DC I saw Guterres give an address about the Syrian refugee crisis. And in a way that would be uncharacteristic of someone who needed Washington’s support to become the next Secretary General, he stood before US government officials at a US government institution and sharply criticized the Obama administration for its (then) paltry commitment to resettling Syrian refugees.

Despite this, he remained popular enough with America for the United States to support his bid to become UN secretary general.

He also developed a reputation as an effective manager. According to figures provided by d’Almeida, Guterres slashed expenditures on headquarters and staff by about half, while simultaneously growing the organization’s capacity to handle larger numbers of refugees. This is fairly impressive given the UN’s famous tendency toward bloat and outright corruption.

This record of success at a particularly difficult task likely explains why he beat out other candidates like Malcorra and Clark, who would have been historic selections.

“He was generally seen as an effective advocate and a competent humanitarian,” David Bosco, a professor at Indiana University who studies the UN, tells me. “Obviously, the fact that he’s being selected at this moment, as the refugee situation in the world is at the top of everyone’s list in terms of urgency — I think that helped him a lot.”

Will Guterres matter?

A key qualification of Guterres is his skill for public outreach — his ability to make a case for refugees and the need to assist refugees that grabs the attention of the world. Public advocacy isn’t the strong suit of Ban, a soft-spoken diplomat who chooses his words carefully and is, to his critics, far too hesitant to criticize major powers like Washington and Moscow.

“In this day and age, the expectation is that the secretary general will have some kind of persuasive power, some ability to use the bully pulpit,” Bosco says. “I don’t think Ban was really able to do that. In that sense, his tenure was kind of crippled.”

This is especially important because the UN secretary general doesn’t have much in the way of formal powers. It’s an important sounding post — leader of the UN. But in truth, that control extends to a few UN agencies, which command budgets tiny in comparison to those of most individual countries.

The true power of a secretary general rests in perception: The sense of legitimacy that comes from being in charge of the world’s largest and most famous international organization. This sense of “speaking for the world” confers a level of notoriety and moral authority; a canny secretary general can leverage that to broker negotiations or spearhead major new humanitarian initiatives.

So the influence of the position — whether, as Bosco puts it, “the secretary general [is] more secretary or general” — depends heavily on the persona in it, as well as the willingness of other countries to listen to the UN at that moment in time.

Guterres will have his work cut out for him. Both Bosco and d'Almeida think his first international priority will be Syria, a problem that no one has a good solution for.

US-Russian negotiations over the country’s future have collapsed, owing largely to Russian support for a renewed Assad offensive against the war-battered city of Aleppo. And even when the US and Russia seemed more on the same page, there was serious doubt that they have the leverage to be able to persuade the actual main parties to the conflicts — the rebels and the Assad government — to arrive at some kind of deal.

It’s not clear if Guterres, no matter how charming or compelling he may be, will be able to persuade anyone to act differently. That’s especially true since the secretary general can’t pick sides in a conflict where the permanent members of the UN Security Council are divided.

But because he’s in charge of the UN, and Syria is the world’s most visible and devastating conflict, Guterres has to at least try. It’s a dilemma that illustrates the basic problem with his new job: The secretary general is supposed to speak for the world, but the world rarely wants to speak with one voice. Without that unity, it’s basically impossible to get anything done.

“The first UN secretary general, Trygve Lie, describe it as ‘the most impossible job in the world,’” Bosco says. “You have all of this demand that the organization respond — but you don’t have the power to make [it].”