(FILES) This file photo taken on June 06, 2017 shows US Secretary of Homeland Security John Kelly testifying during a Senate Homeland Security and Governmental Affairs Committee hearing on Capitol Hill in Washington, D.C. U.S. President Donald Trump on July 28, 2017 ousted his beleaguered chief of staff Reince Priebus, replacing him with retired Marine Corps general and current Homeland Security Secretary John Kelly. (SAUL LOEB/AFP/Getty Images)

Editors’ note: What will the appointment of retired Gen. John Kelly as Chief of Staff mean, particularly for Trump’s foreign policy?  The names may be the different, but this post from November 21, 2016 explains what we know about the politics of advisers.

Speculation is rampant over who will get top appointments in the Trump administration. The potential choices for high-level national-security and foreign-affairs posts have provoked intense interest, in part because of the wide foreign policy divide between candidate Trump and the Republican establishment.

Of these positions, the secretary of state, as the public face of U.S. foreign policy, is arguably the most critical. The next secretary of state may influence the direction of U.S. policy — which itself appears subject to renegotiation in the Trump era.

But research also suggests that even if the president-elect’s choices for secretary of state or other top positions are not significant players in the policy process, the appointments will have implications beyond policy. These appointees will send signals to outside audiences that affect how Congress and the public view Trump’s foreign policy, how it is implemented at the bureaucratic level, and how it is communicated to foreign officials.

We don’t know how much influence Trump’s foreign policy advisers will have

For many positions, including secretary of state, Trump appears to be weighing a choice between a campaign loyalist (such as former New York mayor Rudy Giuliani) and an establishment figure (such as 2012 Republican presidential nominee Mitt Romney, South Carolina Gov. Nikki Haley or Sen. Bob Corker of Tennessee). Apart from Corker, none of the candidates for secretary of state has much substantive foreign-policy experience — and that’s important, because experience can improve strategic bargaining, among other benefits. But an establishment appointee would be seen as far more credible than someone such as Giuliani by the Republican foreign-policy world, as well as by other world leaders. Many in these groups may be hoping that an establishment pick would shift Trump’s policies in the direction of the mainstream GOP.

At the same time, there is no guarantee that an establishment candidate would have a significant influence on policy. The appointee might be marginalized in decision-making, as Colin Powell reportedly was during George W. Bush’s first term. Inexperienced presidents also are less likely to seek a diversity of viewpoints, making such a dynamic more likely.

It’s also possible that Trump will centralize foreign policy in the White House, continuing a trend in recent administrations of both parties. That would make Trump’s reported choice for national security adviser — retired Lt. Gen. Michael T. Flynn, a staunch campaign surrogate whose views and behavior have been heavily criticized as being far outside the Republican mainstream — very influential. To the extent that Flynn’s views clash with an establishment figure’s policy vision, that could lead to further marginalization.

Advisers affect how policies are perceived and sold

Regardless of their effect on policy, though, high-level advisers and Cabinet officials play an important role in signaling the wisdom of an administration’s policies to outside audiences, including members of Congress and the public.

My research shows that when presidents act against their advisers’ public positions, support for policies such as using military force declines markedly. The public views the use of force much more favorably, though, when the president acts as an adviser recommends.

If an establishment appointee such as Romney tacitly or explicitly endorses a Trump administration policy, it would probably be viewed more favorably by the public and in Congress. For Republican administrations that may be perceived as hawkish or aggressive (as Trump and Flynn’s views on the Islamic State, in particular, are), it can be helpful to get the endorsement of an adviser who is known for being more restrained. It was no accident that the Bush administration sent Powell, a known skeptic of the Iraq War, to be a public spokesman for its case. Also, if a Romney-like figure brings more of the formerly “Never Trumpers” onto his team, GOP establishment criticism could grow more muted.

On the other hand, if an establishment figure disagrees with a Trump administration policy enough to speak out against it or even resign in protest, that would signal that something is wrong. Criticism of the president from the opposition party is not nearly as newsworthy as criticism from his own party. Likewise, criticism from an administration figure such as Romney could work as a “fire alarm,” drawing the attention of Congress, the media and the generally inattentive public to the foreign-policy episode at hand. Much would depend, then, on the extent to which an establishment figure is willing to speak out.

Advisers send signals to the rest of the bureaucracy

The presidential appointees also send signals to the rest of the bureaucracy — where much of the day-to-day business of foreign policy is conducted — about the importance of policy and competence vs. personal loyalty to the president in the new administration.

Consider what the appointment of an establishment figure vs. a Trump loyalist would mean to State Department desk officers. As Josh McCrain recently summarized on the Monkey Cage, bureaucrats will work with and respond to presidential appointees who are qualified but not those who are perceived as unqualified loyalists.

Many in the State Department may be looking to see whether an establishment figure — one who might provide a layer of insulation and serve as a potential “fire alarm” — is their new boss. An appointee perceived as an unqualified loyalist, however, may dilute the pool of lower-level talent or lead those who remain to drag their feet in carrying out presidential policy. Of course, some agencies will be more insulated from presidential influence because of the way they are designed.

Advisers, particularly the secretary of state, affect diplomacy

Cabinet officials also attract significant media attention. We know from research by Christopher Deering and the late Lee Sigelman that the “inner Cabinet”— the State, Defense, Justice and Treasury departments — gets the most media attention of the Cabinet, with the secretary of state at the head of the pack.

That is one reason that the secretary of state is the public face of U.S. diplomacy. Research shows that face-to-face diplomacy matters for signaling, communication and interpretation. Most presidents and secretaries of state use foreign travel to maintain America’s diplomatic network — meeting with allies, trading partners and other states of strategic importance. Effective communication is especially important in times of high uncertainty, such as presidential transitions (and leadership turnover more generally). These messages also will matter well beyond the transition for signaling the credibility of U.S. commitments to allies or threats to potential adversaries.

The buck still stops here

But any foreign-policy adviser’s most important audience is the president himself. Presidential power, already robust in the realm of foreign policy, has increased since 9/11. Given Trump’s lack of foreign-policy experience, he probably will be unusually reliant on advisers — at least those he trusts. That will give those advisers significant power without much oversight from the Oval Office. Many presidents have lacked foreign-policy experience. But Trump’s inexperience in combination with the inexperience among his campaign advisers, as well as the chasm between Trump and the Republican foreign-policy establishment, makes the current situation very unusual.

If Flynn becomes Trump’s national security adviser, he is likely to be very powerful. Trump’s remaining appointments will still be critical, even if the secretary of state does not have major input on policy. Bringing establishment figures into the administration would involve trade-offs: the benefits of experience and competence weighed against the potential co-opting of an important group of watchdogs. The daily scrutiny of White House policy, the public and congressional perception of Trump administration decisions, the day-to-day functioning of foreign policy in the bureaucracy, and the communication of foreign policy to world leaders will all be affected by the team Trump that assembles.

Elizabeth N. Saunders is an associate professor of political science and international affairs at George Washington University and a visiting fellow at the Council on Foreign Relations.