The FBI said Wednesday it has “grave concerns” over President Trump’s plans to release a four-page document written by Republican House Intelligence Committee Chair Devin Nunes purporting to show that the FBI abused its power when it began surveilling Trump campaign adviser Carter Page in 2016 due to his dealings with Russia. Supporters of President Trump claim the memo offers proof that the FBI’s investigation was tainted by politics from the start—in part because the FBI won approval of the wiretap by citing a dossier funded by supporters of Hillary Clinton.

The memo is expected to lay blame on the actions of Deputy Attorney General Rod Rosenstein—the same man who is the only official with the authority to fire special prosecutor Robert Mueller. Earlier this week, House Intelligence Committee Republicans voted along party lines to declassify the memo, which had become a rallying cry for President Trump and his supporters. In a highly unusual statement issued on Wednesday, the FBI said it was “provided a limited opportunity to review this memo the day before the committee voted to release it. As expressed during our initial review, we have grave concerns about material omissions of fact that fundamentally impact the memo’s accuracy.” Speaking Wednesday, the ranking Democrat on the House Intelligence Committee, Adam Schiff, echoed the concerns.

Rep. Adam Schiff: “This is not about the facts. This is about a narrative that the chairman wants to put out, a misleading narrative, to undermine the FBI, undermine the department, and ultimately undermine Bob Mueller. And, of course, the danger in all of this, besides the obvious one of politicizing the intelligence process, is that it send a message to the White House that he can fire Rod Rosenstein or he can fire Bob Mueller, and there are GOP members who are so vested in his presidency that they will roll over. And that will cause a constitutional crisis, if that’s the message he takes from this.”

Congressmember Schiff later said that committee chair Devin Nunes had made “material changes” to a version of the memo he sent to the White House and that the changes were not approved by the committee.