Emails unsealed by a judge Tuesday provide context as to why Rick Gates, a former Trump campaign aide, changed lawyers amid special counsel Robert Mueller's federal Russia investigation, according to a report.

Shanlon Wu, who used to represent Gates, complained to members of Mueller's team in one email that they had been meeting with another lawyer, the Associated Press reports. Wu was protesting how prosecutors with the special counsel's office would not discuss the plea offer they were brokering with Gates with him.

The lawyers working for Mueller told Wu the following day they were liaising with Gate's chosen representative, Thomas Green, and did not want to deal with a third party.

Gates pleaded guilty in February to one count of conspiracy against the U.S. and one count of making a false statement stemming from Mueller's Russia probe. He is yet to be sentenced.

The emails were made public one day after the New York Times reported that Gates solicited plans in 2016 from an Israeli company to employ social media manipulation to defeat election rivals.