The classy midfielder has established himself as one of the MLS' best midfield players in recent years and at 24, it is thought that his long-term future lies in one of Europe's top five leagues.
According to the aforementioned source, Newcastle's head of recruitment Steve Nickson traveled to the US recently to discuss terms with Atlanta, with the two parties shaking hands on an initial loan deal until the end of the season when the move will become permanent for a fee of £15m.
A host of other clubs are known to be keen on the midfielder, but Newcastle's proactive approach appears to have put them at the front of the queue.
However, Newcastle boss Rafa Benitez is reportedly not yet certain that owner Mike Ashley will sign off on the deal, with the businessman understood to be in advanced talks with several parties over selling the club.
Ashley is not thought to be willing to spend money in January until talks over a sale reach their conclusion, meaning that whether the takeover is successful or not could have a major impact on the Almiron move.
Almiron scored 12 goals and laid on 13 more in 32 MLS appearances last season as he was named in the division's All-Star XiI for the second consecutive season.