WASHINGTON — The National Archives and Records Administration said Thursday it won’t be able to complete its review of nearly 1 million documents regarding Supreme Court nominee Brett Kavanaugh’s time in the George W. Bush White House until the end of October. This could potentially thwart Republican hopes for quick confirmation before the November election.

The documents being compiled are only the initial request from Republicans. They cover Kavanaugh’s time in the White House counsel office and his nomination to be a judge. But they don’t contain the broader cache of files being sought by Democrats from Kavanaugh’s time as Bush’s staff secretary.

The paper chase is emerging as the biggest battle over President Donald Trump’s nominee as senators scrutinize the record of the 53-year-old conservative appellate judge whose confirmation could tip the court rightward for a generation to come.

Democrats say the documents they are requesting, including the staff secretary papers, are crucial to understanding all aspects Kavanaugh’s background, particular his role in forming policy under Bush.

The chairman of the Judiciary Committee, Sen. Chuck Grassley, R-Iowa, did not immediately respond to a request for comment. But earlier Thursday, he declined to set a date for beginning confirmation hearings, only saying he hoped to start “sometime in September.”

That seems increasingly difficult politically, as Democrats are demanding full access to the documents. Republicans could hold confirmation hearings before receiving all the documents, but a final vote on Kavanaugh may have to wait.

Even before Thursday’s letter from the National Archives, Republicans blasted the Democratic demands as delay tactics. They say senators don’t need to review an additional 1 million papers on Bush-era policies like the interrogation of terror suspects beyond those already being compiled.

Standing before stacks of boxes that will be filled with documents from Kavanaugh’s other jobs — an initial cache is expected later this week — Grassley and other top GOP senators argued there will be ample paperwork to review. They said it didn’t even include Kavanaugh’s 300 cases as an appellate judge.

Grassley called it probably the “deepest dive” ever conducted on a Supreme Court nominee. Since several Democratic senators have already announced their no votes against Kavanaugh, he questioned “the sincerity of demands” for more. “What more do they need to know to vote no?” Grassley asked.

Democrats want to know Kavanaugh’s views on Bush’s signing statements on legislation and other issues.

Particularly concerning to Democrats are Kavanaugh’s writings on the special counsel law after his experience on Kenneth Starr’s team investigating President Bill Clinton.

The issue has become more pressing as Trump tweets, as he did Wednesday, that Attorney General Jeff Sessions should end special counsel Robert Mueller’s probe of Russian interference in the 2016 election. Kavanaugh had earlier suggested such investigations can impede a president’s ability to govern.

As Kavanaugh visits with senators on Capitol Hill — he has met with 47 senators so far, almost all Republicans — questions about his approach to the special counsel law have been raised, senators said.

Democrats say the documents they are requesting, including the staff secretary papers, are crucial to understanding all aspects Kavanaugh’s background, particular his role in forming policy under Bush.

“Getting the documents is especially important,” said Sen. Ron Wyden, D-Ore.