Senior US senators says they were more certain than ever that Saudi Arabia's crown prince, Mohammed bin Salman, was responsible for the killing of journalist Jamal Khashoggi after receiving a CIA briefing on the matter.

"You have to be willfully blind not to come to the conclusion that this was orchestrated and organized by people under the command of MbS," Republican Senator Lindsey Graham told reporters after the meeting with Central Intelligence Agency Director Gina Haspel, referring to the crown prince by his initials.

In his bid to pressure the Trump administration to condemn the crown prince, Graham, who has become one of the president's most vocal allies, said there may not be a "smoking gun," but that there was a "smoking saw," a reference to a bone saw that investigators said was used to cut up Khashoggi's body.

Making some of their strongest accusations so far, both Republicans and Democrats said they still want to pass legislation to send a message to Saudi Arabia that the United States condemns the death of Khashoggi. But they remain sharply divided over how to do so.

Many Democrats want a "straight up or down vote" on a war powers resolution to end all US support for the Saudi coalition in Yemen, without amendments.

But President Donald Trump and some of his fellow Republicans have argued that Washington should not take action that would risk its relationship with Riyadh, which is viewed as an important counterweight to Iran in the Middle East.

"Somebody should be punished," Republican Senator Richard Shelby said. "Now the question is how do you separate the Saudi crown prince and his group from the nation itself?"

Last week, 14 of Trump's fellow Republicans, who hold a slim majority in the Senate and rarely break from the president, defied his wishes and voted with Democrats to advance the measure that would end US support for the Saudi-led war effort in Yemen.

The unusual vote last week came shortly after a briefing by Trump's Secretary of State Mike Pompeo and Secretary of Defense Jim Mattis, who urged lawmakers not to do anything to undermine the US-Saudi relationship.

Haspel's absence from that briefing angered senators.

Graham said he would not vote for the Yemen resolution. He said he would prefer to pass a separate bill to cut off arms sales to Saudi Arabia, military aid for the war in Yemen and impose sanctions on those responsible for individuals responsible for human rights abuses.

Graham introduced a bill setting out those goals last month. Democratic Senator Bob Menendez, another lead sponsor of the legislation, told reporters after the Haspel briefing that he might try to get it passed as an amendment to a must-pass spending bill if the Senate does not pass the war powers resolution.

Both Republicans and Democrats urged Trump himself to strongly condemn the killing after he stood by the crown prince.

"If the crown prince went in front of a jury, he'd be convicted in 30 minutes," said Senator Bob Corker, the Republican chairman of the Senate Foreign Relations Committee. Asked if he would be convicted of murder, Corker replied "Yes."

The senators spoke to reporters as they left the closed-door briefing for some Senate committee leaders and Senate leaders by CIA Director Haspel.

"Before this briefing, I was convinced that we had to take steps on the war in Yemen and I believe that we had to take steps on the Saudis,” Menendez said. "I am only solidified in that view after this briefing. It is my hope that the Senate will act and send a strong, unequivocal message that such actions cannot stand and I believe that my legislation with Senator Graham is the appropriate response."

Corker shook his head no, when asked if he thought Haspel's Senate briefing on Tuesday had changed any minds.

Khashoggi, a US resident who was a columnist for the Washington Post, was killed inside the Saudi consulate in Istanbul in October.

Senators acknowledged there are still deep divides between the two parties on how to proceed.

Corker said it would be "difficult" to come up with legislation that could pass the Senate. He said he was working with colleagues on how to amend the resolution, and he had not had suggestions from the Trump administration on how it might prefer to proceed.