The State Department hit out at delays and infighting in the Senate that have led to a backlog of hearings to confirm new US ambassadors.
Two nomination hearings had been due to be held by the Senate Foreign Relations committee on Thursday for 10 nominees to vacant posts, including the next envoy to key Washington ally Saudi Arabia.
But the hearings were postponed at the last minute when a Republican senator objected.
Both Republicans and Democrats have to agree to let hearings proceed but a Republican lawmaker raised an objection just before they were due to take place, a Senate aide told AFP.
"We were alarmed today to see another 11th-hour delay," State Department deputy spokeswoman Marie Harf told reporters.
There were currently 67 department nominees awaiting confirmation, she said.
"We believe it would be a real problem if this process drags on any longer because of Senate infighting," she added, highlighting that Congress will soon close for the end of year holidays.
Apart from the inconvenience to family and friends who often travel long distances to support a nominee at the hearing, at least one foreign ambassador had also been told to go home.
"This doesn't speak well to the functioning of our government, I think, to our partners overseas as well," Harf added.