Mr. Merkley asked Mr. Fischer to provide the committee with a detailed explanation of the case, a request Mr. Fischer promised to fulfill. Such belated back-and-forths often delay confirmations by weeks or months.

Another nomination that is in limbo is that of Doug Manchester, nominated to be ambassador to the Bahamas, who last year described the sovereign state as, “for all intents and purposes,” a protectorate of the United States, a description that was not well received on the islands, which have historical ties to Britain.

“There’s a great frustration with our friends, who say there’s no one to talk to. And Pompeo can’t do it all himself,” said James J. Carafano, a fellow at the Heritage Foundation and a member of the Trump transition team, who added that the department’s many vacancies were “a self-inflicted wound.”

Special envoys do not need to go through a confirmation process, and White House approval for the selections is said to be more lenient. Last week, Mr. Pompeo announced the appointment of James F. Jeffrey as a special envoy for Syria. In 2016, Mr. Jeffrey was one of 50 senior Republican national security officials to sign a letter saying Mr. Trump “would put at risk our country’s national security and well-being.”

The White House has avoided those who signed such letters for Senate-confirmed slots.

“Pompeo has to construct a team and fast, and appointing special envoys is one way to do that,” said Thomas A. Shannon, who recently retired as the department’s highest-ranking career diplomat. “And I think these latest choices are inspired.”

Stephen E. Biegun, an executive at the Ford Motor Company and a White House aide in the George W. Bush administration, was named on Thursday by Mr. Pompeo to be the senior envoy leading negotiations with North Korea. The two will head to Pyongyang next week, which will be Mr. Pompeo’s fourth trip there.

Mr. Pompeo canceled a July meeting with top Indian diplomats to make his third trip to Pyongyang, a decision that caused bruised feelings in New Delhi — a reminder of how much help he needs.