Rep. Adam Schiff (D-CA) made a last-minute effort Wednesday evening to block the release of a highly-anticipated House Intelligence Committee memorandum that is expected to allege that the Obama administration abused the federal government’s surveillance powers to spy on Donald Trump’s political campaign.

The committee voted along party lines on Monday to release the memorandum to the public, subject to final approval by the president.

Schiff, the ranking member of the Democratic Party minority on the committee, tweeted that committee chair Rep. Devin Nunes (R-CA) had “made material changes to the memo he sent to White House.” Because these changes had not been formally approved by the committee, he said, the president was “therefore reviewing a document the Committee has not approved for release.”

He tweeted images of a letter addressed to Rep. Nunes in which he said there was “no longer a valid basis for the White House to review” the document, and demanded it be withdrawn.

BREAKING: Discovered late tonight that Chairman Nunes made material changes to the memo he sent to White House – changes not approved by the Committee. White House therefore reviewing a document the Committee has not approved for release. pic.twitter.com/llhQK9L7l6 — Adam Schiff (@RepAdamSchiff) February 1, 2018

Shifts accusations follow a pattern established last year, when he demanded that Nunes recuse himself from the investigation into possible Russian interference in the 2016 presidential election after the chairman exposed the Obama administration’s practice of “unmasking” the names of U.S. citizens who had been under surveillance. Nunes was accused of coordinating with the White House. He was later cleared by the House Ethics Committte.

The committee’s GOP majority responded to Schiff’s claims via Byron York of the Washington Examiner, calling his claims a “strange attempt to thwart publication of the memo.” While admitting that some changes had been made, York’s “Intel source” said that they were “minor edits,” including one made at the behest of Democrats.

Just talked with House Intel source. Said total changes to memo were: A) Unknown number of ‘grammatical and clarifying’ fixes. B) One change requested by FBI due to sources & methods concerns. C) One two-word change requested by Democrats for accuracy. House Intel GOP statement: pic.twitter.com/ZkNuMBoLZK — Byron York (@ByronYork) February 1, 2018

News reports suggested that the White House could release the memorandum as early as Thursday. The Democrats’ own memorandum will be reviewed by House members and could be released to the public the following week.

Earlier Wednesday, Nunes hinted at the memo’s contents in responding to the FBI’s objections to its release: “[I]t’s no surprise to see the FBI and DOJ issue spurious objections to allowing the American people to see information related to surveillance abuses at these agencies … [I]t’s clear that top [FBI] officials used unverified information in a court document to fuel a counter-intelligence investigation during an American political campaign.”

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He was named to Forward’s 50 “most influential” Jews in 2017. He is the co-author of How Trump Won: The Inside Story of a Revolution, is available from Regnery. Follow him on Twitter at @joelpollak.