Callista Gingrich, U.S. ambassador to the Vatican, with Pope Francis at a Jan. 8 audience with diplomats celebrating the New Year. (Andrew Medichini AFP/Getty Images)

After a year of President Trump's Twitter diplomacy, speculation about the fate of Secretary of State Rex Tillerson, and reports of chaos at the State Department, it's easy to forget about the ambassadors.

Aside from the secretary of state, ambassadors are the most visible — and personal — representatives of the president's foreign policy worldwide. Traditionally, campaign donors and close friends are rewarded with plum postings, and this administration is no exception: The Senate has already confirmed more than two dozen Trump picks, notably for China, Russia, Israel, Britain and France.

But there are also curious gaps: There are no ambassadors to Germany, the European Union or South Korea.

Before his inauguration, Trump required all of President Obama's political ambassadors to leave their posts on Jan. 20. The directive has left some countries without an ambassador for more than a year — something that many view as a personal snub. "This is now bordering on a diplomatic insult," Australia's former deputy prime minister Tim Fischer said last week.

Most presidents give about a third of top embassy spots to political appointees; the rest are filled by career diplomats. It typically takes months for a nominee to go through the confirmation process, although the Senate fast-tracked Nikki Haley, approving her as ambassador to the United Nations on Jan. 24, 2017. David Friedman, Trump's bankruptcy lawyer, was confirmed as ambassador to Israel in March, and Iowa Gov. Terry Branstad was confirmed for China in May.

Then things stalled.

"Dems are taking forever to approve my people, including Ambassadors," Trump tweeted in June. "They are nothing but OBSTRUCTIONISTS! Want approvals."

Of course, the reality is more complicated. Although several names for ambassadorships were floated early on, the administration has been slow to formally nominate its selections. On the day before his inauguration, Trump announced that billionaire Robert "Woody" Johnson, owner of the New York Jets and a generous donor to the president's campaign, was his pick for the prestigious posting to London. But Johnson's name wasn't sent to the Senate until June; he was confirmed in August.

U.S. Ambassador Jon Huntsman with Russian President Vladi­mir Putin at a credential presentation in the Kremlin on Oct. 3. (Pavel Golovkin/EPA-EFE) (Go/Pool/Epa-Efe/Rex/Shutterstock/Go/Pool/Epa-Efe/Rex/Shutterstock)

Some embassies went to familiar names: Jon Huntsman, former governor of Utah and ambassador to China, was tapped for what is probably the most sensitive diplomatic posting of the administration — Russia. Scott Brown, a former senator from Massachusetts, is in New Zealand, and former senator Kay Bailey Hutchison of Texas was named ambassador to NATO.

A number of other ambassadors were confirmed in the late summer and fall, many wealthy donors to Trump and the Republican National Committee. The White House selected business executive Kelly Knight Craft as envoy to Canada; investor Lewis Eisenberg for Italy; investor George Glass for Portugal; and William Hagerty, a member of Trump's transition team, for Japan.

France went to Jamie McCourt, former co-owner of the Los Angeles Dodgers. Callista Gingrich, wife of former House speaker Newt Gingrich, landed the spot at the Vatican. Ed McMullen, a public relations expert who served on the Trump transition team, was named ambassador to Switzerland.

Spain is reportedly delighted that financier Duke Buchan is heading the U.S. embassy in Madrid, primarily because he studied in the country and is fluent in Spanish. Ken Juster, a Harvard lawyer and economic expert, is being warmly welcomed in India. But the newly confirmed ambassador to the Netherlands, Pete Hoekstra, landed with a thud.

Pete Hoekstra, new U.S. ambassador to the Netherlands, center, arrives at Palace Noordeinde in The Hague to present his credentials to Dutch King Willem-Alexander. (Peter Dejong)

Last month, a Dutch reporter asked Hoekstra why he said there were places in the Netherlands where radical Muslims were burning cars and politicians. Hoekstra denied making that comment, calling it "fake news." After the reporter played a tape of the former Michigan congressman saying exactly that. Hoekstra denied having used the term "fake news" just moments earlier. And at his first official news conference this week, the new ambassador refused to answer multiple questions about the incident. It was all, well, odd.

Although most of Trump's picks have sailed through the confirmation process, not everyone has been rubber-stamped. In September, Trump nominated Richard Grenell, a former U.S. spokesman at the United Nations, as ambassador to Germany.

Some senators took issue with Grenell's partisan attacks in appearances on Fox News. "There are few professions that probably prepare you worse for being a diplomat than being a cable news commentator," Sen. Chris Murphy (D-Conn.) said at Grenell's confirmation hearing. Other senators were offended by tweets about female political figures' looks. The Senate never scheduled a full vote on the nomination.

The White House renominated Grenell this week, along with former White House deputy national security adviser K.T. McFarland as ambassador to Singapore. McFarland was nominated in May but was stalled amid questions about her ties to Gen. Michael Flynn and Russia.

Former ambassador Ronald Neumann, a career diplomat who headed the embassies in Afghanistan, Algeria, and Bahrain, calls Trump's ambassadors a "mixed bag. Some are apparently good, some weak. The question is: Do you send people without diplomatic qualifications to countries with sensitive political issues?"

Like South Korea, for example. Despite the president's heated rhetoric about North Korea, the administration has not formally nominated anyone to serve as ambassador to Seoul. Victor Cha, an academic from Georgetown University's School of Foreign Service and the Center for International and Strategic Studies, is widely rumored to be under consideration for the post. But unless the nomination moves with unusual speed, it's unlikely that Cha would be confirmed in time to weigh in on the current bilateral talks between North and South Korea, or for next month's Olympic Games in PyeongChang.

Other notable countries without ambassadorial nominees: Argentina, Austria, Belgium, Egypt, Hungary, Ireland, Jordan and South Africa. And although Trump was greeted with a lavish state visit last year, he has not named anyone to serve in Saudi Arabia.

The State Department did not respond to requests for comment about the confirmations or unfilled positions.

Secretary of State Rex Tillerson has been criticized for delays in filling ambassadorial vacancies. (Carlos Barria/Reuters)

"We're still awaiting a lot of nominees to clear the processes and be confirmed," Secretary of State Tillerson said last month in Brussels. "I get a little criticism for that from time to time."

The delays appear to be a matter of nominating people that both the president and Tillerson can agree on — the secretary of state has reportedly pushed back at some of the president's more controversial picks.

"The impression is that a lot of the slowdown is between the State Department and the White House," said Neumann, now president of the nonpartisan American Academy of Diplomacy.

White House spokeswoman Sarah Huckabee Sanders, however, told ABC News that "we have worked closely with the State Department to get ambassadorship positions filled and have had great success in getting some of the most qualified and credible individuals in place to serve as representatives for our country."