(CNN)Special counsel Robert Mueller has issued a subpoena to the Trump campaign for more Russia-related documents, two sources familiar with the matter tell CNN.
Special counsel subpoenas Trump campaign for more documents
The Wall Street Journal first reported on the request.
The special counsel had previously received the information that had already been handed over to Congress, but investigators felt there were things they didn't see. The new subpoena seeks more records based on various search terms.
One source described it as a "cleanup" subpoena, expanding the search terms. The campaign is in the process of complying, the source said.
The White House has not received a similar subpoena, CNN is told.
Both the Trump campaign and a lawyer for the Trump campaign did not respond to a request for comment.
The second source calls the subpoena "bookkeeping" at the end of a grand jury process. That source called the subpoena "largely perfunctory" and said much of it will be "duplicative" of documents the special counsel already has.
One source says fulfilling the new request could take months because of the amount being asked for, while the other says it likely won't delay things beyond January.
The special counsel is investigating possible ties between the Trump campaign and Russia from the 2016 election.
Last month, former Trump campaign chairman Paul Manafort and former Trump campaign official Rick Gates surrendered to Mueller and pleaded not guilty after an indictment contained 12 counts against them, and former Trump campaign foreign-policy adviser George Papadopoulos pleaded guilty to making a false statement to the FBI after he lied about his interactions with foreign officials close to the Russian government.