Over the next few days, many smart people will opine on the prospects for success of António Guterres, the man (yes, surprise, another man) nominated by the United Nations Security Council to be the next UN secretary-general.

Given the ongoing global refugee crisis, persistent conflict, and the looming threat of more climate-related disasters, many will call on Guterres to ensure that humanitarian issues are not routinely shunted aside at the Security Council and General Assembly by purported “hard power” issues, as they often are. A safe assumption, given Guterres’ 10 years of experience serving as UN High Commissioner for Refugees (UNHCR), is that he will try.

Indeed, in remarks following the nomination announcement, Guterres stressed his commitment to focusing needed attention on refugees and children: “Our collective failures to meet core needs can lead to escalating tragedies for those who are already among the most vulnerable in the world.” 

But he will face many challenges in wrangling member states to address humanitarian concerns. Here are five likely sources of tension between Guterres’ humanitarian past and his political future:

1. Like a new car, no secretary-general retains full resale value once driven off the lot. Guterres earned plaudits while at UNHCR for competence and principles. But it is relatively easier to be popular when you work on behalf of humanitarian victims than when you have to herd a world full of dictators, war criminals, and sovereignty enforcers toward difficult political agreements, as he will now be required to do. He should enjoy this brief period basking in acclaim before the inevitable sniping starts. 
2. Guterres has mastered the pulpit, but can he bully? Guterres has at key times served as world conscience on acute humanitarian crises like Syria and the European refugee crisis. To exert influence as secretary-general, however, he will need skills that are more LBJ than Dalai Lama. As the first former head of government to lead the UN (he was prime minister of Portugal from 1995-2002), he should have a bag of political/lobbying tricks from which to draw.
3. Will he cope with the UN, or try to reform it? One area where Guterres might exert significant personal influence is on institutional reform, especially of the operations and mandates of humanitarian agencies. I’m sure there will be those at the International Organization for Migration, the Office for the Coordination of Humanitarian Affairs, and other UN entities who fear he will try to empower UNHCR at their expense. Guterres knows the strengths and weaknesses of the current system, however, and could be a persuasive salesman for consolidation and coordination.
4. Will he spend time on symptoms or root causes (i.e., will he be good or great)? Like pre-school teachers, humanitarian workers resign themselves to cleaning up messes they didn’t create. If Guterres devotes his time to making the humanitarian system more efficient and effective, he will likely be remembered as a good secretary-general. But if he can also mobilize multilateral force to address the dreadful conflicts that create the world’s worst humanitarian crises – understanding that, in the secretary-general job, great ambitions often earn diplomatic enemies – he could be great.
5. How will he handle his most important, and difficult, relationship? Americans will expect too much of Guterres, as we do with every secretary-general, and then complain when he doesn’t accomplish what we can’t accomplish ourselves. In his new job, Guterres will be subject to even greater diplomatic pressure to demonstrate independence from Washington. (As UN watchers know, that the U.S. is the largest funder of the UN and UN peacekeeping operations has not automatically translated into acquiescence to our wishes.) We should remember, however, our good fortune it was Europe’s turn to hold the secretary-general position, which meant the pool of candidates was more pro-American than usual. U.S. government officials have enjoyed very good working relations with Guterres, and that will likely continue. 

Blaming secretaries-general for the state of the world is like blaming a baseball manager for losing a World Series. It is not entirely fair, since pitchers and position players have much more influence on the final score, but we do it anyway.

Guterres could very well be an excellent secretary-general, and lead positive change regarding how the UN mitigates humanitarian crises and resolves them. But the world is dangerous, multilateral diplomacy is slippery, and we had best keep our expectations reasonable.