Washington (CNN) -- Sen. John McCain said Monday he would lift a "hold" on the confirmation of James Clapper to be the Director of National Intelligence if he receives a report he's requested for the past 18 months.
Brooke Buchanan, McCain's spokeswoman, had said earlier in the day that the Arizona Republican would hold up a Senate vote on Clapper because he never received the report.
Later in the day, McCain said he received assurances he would get the report "tonight or tomorrow," and that once he gets it, he will lift his hold. McCain also said he was likely to vote for Clapper's confirmation.
"As an ex officio member of the intelligence committee and senior Republican on the Senate Armed Services Committee, I expect when people look me in the eye and say, 'I'll get a report over to you,' that it comes over," McCain said. "That's what I really care about. Congressional oversight."
Senate Democrats hoped to clear Clapper's confirmation before the August recess, which begins at the end of the week. Unless Clapper satisfies McCain's request, Clapper will likely have to wait until mid-September when the Senate returns to work.
Buchanan would not provide the subject matter nor other details of the report McCain has requested.
Clapper's office at the Pentagon had no comment on the hold.
If Clapper's confirmation is delayed, there could be a huge vacuum at the top of the intelligence community because Deputy DNI David Gompert, who is currently the acting Director of National Intelligence, is resigning at the end of August.
Senators are allowed to put "holds" on nominees or legislation as a signal to the Senate leadership that they might filibuster a vote on the matter until their issues are resolved.
White House spokesman Tommy Vietor called for quick confirmation of "this critical nomination."
"The Senate Intelligence Committee's unanimous approval of Mr. Clapper's nomination last week -- after hours of testimony and countless documents were provided to the Committee -- is a testament to the fact that he is one of our nation's most experienced and respected intelligence professionals," Vietor said in a statement.
CNN's Pam Benson and Suzanne Malveaux contributed to this report.