Joe Biden is sticking to tradition as he slowly fills the vacancies in the ranks of ambassadors across the world, focussing on mixing longtime career diplomatic officials with figures with strong ties to himself and the Democratic party.

Among Biden’s expected picks is Caroline Kennedy, former US ambassador to Japan, daughter of the former president, and longtime Biden friend, ally and donor, to be ambassador to Australia. He has picked the Los Angeles mayor, Eric Garcetti, who was a prominent Biden surrogate on the presidential campaign trail, to be ambassador to India, despite a relative lack of foreign policy experience. And the president is also widely expected to name the former Chicago mayor Rahm Emanuel ambassador to Japan.

These choices, which are expected to be put forward for confirmation in the coming weeks, and the many others nominated so far, have gradually answered a persistent question hanging over Biden’s presidency: how he would approach filling out the ambassadorial ranks and follow through on his vow to reengage the world as president.

Biden’s selections appear to thwart the pressure from the progressive wing of his party to depart from tradition, in which new presidents give out plum roles to top donors and high-profile figures with strong ties to the president.

The Massachusetts Senator Elizabeth Warren, Biden’s former progressive rival for the Democratic presidential nomination, is among those who have strongly argued that career civil diplomats and foreign affairs experts should get ambassadorial posts, regardless of how close they are to the administration in power or how much money they donate.

Biden’s expected appointments have left some longtime career diplomats frustrated.

“The frustration a lot of them have is not just that we’re getting lots of political ambassadors and political appointees at the state department, but that Biden came over early in his presidency and talked about ‘we’re going to elevate career diplomats, we’re going to empower you’, and so it makes it all the more disingenuous and disappointing,” said Brett Plitt Bruen, a former foreign service officer and director of global engagement during Barack Obama’s presidency.

“America’s influence in the world is at a historic low, so the notion that we’re going to send movie moguls and fashion designers and political donors to repair is antithetical to everything that Biden has talked about.”

Bruen added that the trend among Biden’s political ambassador picks is that “they all have a personal connection,” from the top international postings to the less high-profile. For example, Chesley “Sully” Sullenberger, the airline captain who tackled the emergency landing of a US Airways plane on the Hudson River in 2009 with no fatalities, served as a surrogate on Biden’s campaign and is expected to be tapped for ambassador to the International Civil Aviation Organization.

“This isn’t how it should work. The qualifications for representing the United States should be based on national security criteria, not on a personal relationship to the president,” Bruen continued.

In the past few days, Biden has nominated the former Republican senator Jeff Flake of Arizona to serve as ambassador to Turkey and the former senator Tom Udall of New Mexico to be ambassador to New Zealand. He has also picked Cindy McCain, the wife of the late senator John McCain of Arizona, to be ambassador to the United Nations Agencies for Food and Agriculture. He has picked Denise Bauer, a former ambassador to Belgium, to be ambassador to France.

According to the American Foreign Service Association’s (AFSA) ambassador tracker, as of Friday, out of 45 ambassadorial nominations Biden has made, 48.9% are career appointments and 51.1% are non-career appointments. There are a total of 189 positions to appoint.

“We estimate 80 ambassadorships are still unfilled. Some have been nominated but not confirmed, about half,” former ambassador Eric Rubin, the president of AFSA, said in an email.

Some observers have noted that Biden’s most high-profile diplomatic appointments have long career resumes, such as Linda Thomas-Greenfield, the Biden administration’s pick for ambassador to the United Nations, and Jane Hartley, a former ambassador to France who is Biden’s choice to be ambassador to the UK.

Biden has also picked Ken Salazar, a former attorney general and senator from Colorado who served as interior secretary during Barack Obama’s presidency, as ambassador to Mexico. Tom Nides, a former deputy secretary of state during the Obama administration who more recently has worked at Morgan Stanley, is Biden’s nominee to be ambassador to Israel. Recently, the Biden administration announced that Jill Biden’s chief of staff, Julissa Reynoso Pantaleón, a former ambassador to Uruguay, would be ambassador to Spain.

Career officials interviewed by the Guardian also noted that as important as experience is, closeness to the president is often seen as an important asset.

“You send your best ambassadors to the most important countries,” said Adam Ereli, a former ambassador to Bahrain. He ticked off China, Russia and Japan as a few of those countries in Asia. In Europe he said the critical nations are Germany, England, France and arguably Turkey. Nicholas Burns, a former undersecretary for political affairs at the state department, is widely rumored to be Biden’s pick to be ambassador to China.

One of the most important qualifications, Ereli said, is “closeness to the president – because that’s what the countries want, they want someone who can pick up the phone and talk to the president”.

The Biden administration has been comparatively slower than its predecessors to fill out vital ambassadorships, even as in other areas of the federal government the president’s team has moved swiftly to nominate and install judges and officials.

“It’s hard to understand why it’s the middle of July and a lot of ambassadorships are not nominated yet,” said Rubin. “And honestly if the White House says that’s because of vetting, then the question is why has every other administration managed to do that faster?”