CIA Director Gina Haspel was conspicuously absent from a Capitol Hill briefing on military aid to Saudi Arabia Wednesday, a decision Democratic Whip Dick Durbin said Secretary of State Mike Pompeo and Defense Secretary Jim Mattis told senators was at the White House's direction.

"We asked why Gina Haspel wasn't there and the two that were there said that was a decision by the White House," Durbin told reporters following the briefing.

Trump ally Republican Sen. Lindsey Graham threatened he wouldn't vote for a spending bill until he hears from the CIA directly.

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"If that briefing is not given soon, it's going to be hard for me to vote for any spending bill," Graham told reporters, adding when asked for clarification, "I'm talking about any key vote anything you need me for to get out of town, I ain't doing it until we hear from the CIA."

The explanation offered Wednesday for Haspel's absence flatly contradicted national security adviser John Bolton on Tuesday — Bolton claimed the White House was not blocking Haspel from testifying. Haspel is the sole official of the three reported to have listened to the audio that allegedly depicts the killing of Jamal Khashoggi, the Saudi journalist was killed by Saudi operatives in the Saudi consulate in Istanbul last month.

The CIA also pushed back on the claim that anyone prevented Haspel from attending. CIA Press Secretary Timothy Barrett said the "notion that anyone told Director Haspel not to attend today's briefing is false."

The briefing with Pompeo, Mattis and senators on Capitol Hill Wednesday comes ahead of a vote they're expected to take on cutting off military aid to Saudi Arabia for a war in Yemen. Pompeo and Mattis argued Wednesday that U.S. involvement there is critical — but both Republican and Democratic senators who spoke with reporters after the briefing seemed less convinced of that.

The CIA has intelligence substantiating an assessment the crown prince ordered Khashoggi's killing. The CIA's assessment appeared to be largely based on the control held by the crown prince. In other words, the thinking is the murder could not have been carried out without the knowledge of the crown prince, often referred to by his initials, MBS.

Pompeo told reporters after the briefing that "there is no direct reporting connecting the crown prince to the order to murder Jamal Khashoggi." Defense Secretary Jim Mattis later spoke along similar lines, saying at the Pentagon "we have no smoking gun that the crown prince was involved."

But Sen. Chris Murphy, D-Conn., told reporters Mattis and Pompeo did not deny reports that the Saudi crown prince was involved in Khashoggi's death. Mr. Trump has repeatedly insisted the CIA has come to no conclusion over Khashoggi's death, and defended the Saudis over the murder.

Pompeo's unclassified prepared remarks to Congress made no mention of Khashoggi, although he did call the murder a "heinous" act in speaking with reporters later.

Senators were visibly frustrated with Haspel's absence.

"I wish she would have been there, a lot of us were frustrated that she wasn't," Republican Sen. Jeff Flake said, adding, "Nobody was happy that she wasn't there, put it that way."

Sen. Bob Menendez, D-New Jersey, called it "outrageous" that the Senate would be stonewalled from hearing from the CIA director.

"It tells me volumes about what's really going on here," Menendez said.

Pressed twice by reporters on why Haspel didn't appear, Pompeo responded twice: "I was asked to be here, and I'm here."

Alan He, Nancy Cordes, Olivia Gazis, Kathryn Watson, Grace Segers and John Nolen contributed to this report.