(CNN) When President Donald Trump travels to Southeast Asia this fall, he will likely be going without the help of one key adviser: a chief of protocol.

Vice President Mike Pence announced Thursday that the President will attend two summits in the Philippines and one in Vietnam this November, and before that, he has trips planned to Brussels, Italy and Germany this spring and summer. But since January 20, there has been no one officially in the important diplomatic position -- and once someone is named it takes months, or even more than a year, for a nominee to be confirmed by the Senate.

There are more high-profile positions that require Senate confirmation that are still open -- among them are ambassadorships to Afghanistan, France and South Korea, according to the American Foreign Service Association's website. But the chief of protocol is an often misunderstood or entirely overlooked position that serves an important function and has been an official posting since just after the end of World War II.

What they do

Chiefs of protocol work at the State Department, and since 1961, they have all held the rank of ambassador. They are sometimes former ambassadors themselves and are well-versed in foreign relations and etiquette. They accompany presidents on foreign trips and coordinate visits of foreign dignitaries to the US, they greet newly installed ambassadors moving to Washington, they help select gifts for foreign leaders and they run Blair House, the historic guesthouse across the street from the White House.

"The whole concept of protocol is to create the framework for diplomacy," said Capricia Marshall, who was chief of protocol during the Obama administration. "We work through all the details before the two leaders set foot in the room because you want their focus to be the very serious discussions they're going to engage in."

One of their jobs is to never allow the President or the first lady to be embarrassed. When the Obamas first visited the United Kingdom, members of the British press were aghast when first lady Michelle Obama briefly put her hand on Queen Elizabeth II's back during a reception, bucking royal protocol that no one touches the Queen. It is the job of the chief of protocol to make sure that scenes like that do not happen, but Marshall was awaiting confirmation at the time. (The Trumps are expected to go to the United Kingdom for a state visit, likely this fall.)

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Vacant periods

There have been periods when the office was vacant while a nominee is awaiting Senate confirmation and a career employee at the State Department has filled the position until a nominee is confirmed. According to two people familiar with the office, deputy chief of protocol Rosemarie Pauli is acting as chief until a nominee is confirmed. But the fact that no one has been put up for confirmation yet is unusual.

President George W. Bush asked Don Ensenat to be his chief of protocol shortly after January 20, 2001, and then-Secretary of State Hillary Clinton put Marshall's name forward for Obama's consideration shortly after his inauguration.

President Donald Trump and first lady Melania Trump pose with Chinese President Xi Jinping and his wife Peng Liyuan upon their arrival to the Mar-a-Lago estate in West Palm Beach, Florida, on April 6, 2017.

The White House did not respond to a CNN request for comment.

Without someone in the position, oversights have already happened during the Trump administration.

"I cringe when I see President Xi (of China) sitting to the left of President Trump," said a former American diplomat. "You should always have your place of prominence to your right because you're showing your guests respect."

So far, Trump seems more relaxed about protocol, though, and even comes to the door of the West Wing to greet foreign leaders himself, adding a personal touch that used to be the job of the chief of protocol.

The chief of protocol is sometimes the first American with whom foreign diplomats ever speak at length when they go to the State Department to present their documentation from their foreign office making them an ambassador. This process will still go on without a chief of protocol in place because career staff at the State Department, who stay in their jobs regardless of who is president, will fill the void. But not having someone in the post is a missed opportunity, former diplomats said. One former diplomat in the Obama administration likened it to a senator's office with no senator.

"One thing that's missing is having a de facto representative of the President who is focused on constituent services and that constituency is the diplomatic corps," the person said on the condition of anonymity.

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Not a priority?

Tyler Abell, chief of protocol during President Lyndon Johnson's administration, said he is not worried if the position goes unfilled for a while.

"Somebody has to do the job and they don't need to be sitting at a desk with the title of 'chief of protocol' on it," he said. "A lot of work is run of the mill."

It took Nancy Brinker, who served as US ambassador to Hungary from 2001 to 2003 and as Bush's White House chief of protocol from 2007 to 2009, more than a year to be confirmed. Brinker said whomever Trump nominates should understand diplomacy and hospitality.

"The farther you go from the US the more important it becomes. There's a tremendous amount of message in gestures," she said.

Another key component of the job is making sure that visiting leaders are happy. For instance, Brinker said, when the president of Mongolia came to Washington he wanted to visit Arlington National Cemetery, so she and her staff arranged for it. Brinker met with Trump in March but they did not discuss the position at any length.

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Consequential position

The responsibilities of the job are more consequential than they seem.

"You have to think of this in human terms and think about basic needs. You don't want a hangry diplomat," Marshall said.

She was referring to a meeting between Obama, Israeli Prime Minister Benjamin Netanyahu and Palestinian President Mahmoud Abbas in New York when she was so focused on other details that she forgot to provide food for the delegations. When she asked Netanyahu if he needed anything, he replied, "A cup of coffee and a cookie would be nice."

Embarrassed, she raced to the hotel kitchen.

Ensenat, Bush's chief of protocol from 2001 to 2007, said he offered to help the Trump administration with names and guidance but has not heard back.

"For the leader that you're interfacing with, having someone they can always look to from big things to little things is important," he said. "The hosts don't want to deal with some advance man who is 20 years old."

It is the chief of protocol who briefs the President on the customs of other countries. It can be as simple as telling the President a traditional greeting in the native speaker's tongue or making sure he knows that a certain head of state is fasting so he will not be eating lunch that day. Sometimes on visits to foreign countries or during a meeting with a visiting dignitary, only those with ambassador rank are allowed in the room, so by default, the chief of protocol is the last person to brief the president.

"I'm worried they'll name some Manhattan socialite," Ensenat said of Trump's deliberations "It's totally the wrong job for a socialite, they'll be disappointed. It's not a glam job. It's nitty-gritty work."