Kristian Dyer reported in Metro on Wednesday that Stewart is "the favorite" for the role, created by current US Soccer president Carlos Cordeiro. That report was subsequently followed up on Wednesday by Yahoo Sports' Doug McIntyre, who said Stewart is in negotiations to take the job.
The GM will be responsible for hiring the next permanent USMNT head coach, with the role currently filled by Dave Sarachan.
MLSsoccer.com's Sam Stejskal reported in April that Stewart was one of the candidates interviewed for the position. According to Dyer's report, "The source, speaking to Metro on the condition of anonymity, said that Stewart is believed to be the frontrunner and is in negotiations for the position following an impressive showing during the interview process."
Stewart, 49, has been Union sporting director since October 2015. Prior to that, he served similar roles in his second country, the Netherlands, at AZ Alkmaar and NAC Breda. The midfielder, who played 17 seasons at professional level in the Netherlands and for D.C. United, was a US international, earning 101 caps in his playing career.