There's a growing list of top Senate Republicans who've come forward and said they believe Saudi Crown Prince Mohammed bin Salman ordered the killing of Washington Post columnist Jamal Khashoggi.

Khashoggi, a Saudi national who was often critical of the royal family in his writing, was killed in the Saudi consulate in Istanbul on October 2.

The CIA has reportedly concluded the Saudi crown prince, the de facto ruler of the kingdom, ordered the killing.

But President Donald Trump has forcefully defended the Saudi royal family over Khashoggi's killing and signaled he does not wish to punish the crown prince over the incident. As a result, the president has been accused of siding with the Saudis over the US intelligence community.

Read more: Trump slammed by Turkey's top diplomat for turning a 'blind eye' to Khashoggi after president says CIA only has 'feelings' on killing

Last week, senators expressed outrage over the fact CIA Director Gina Haspel was absent from a briefing on Khashoggi's killing. Haspel was reportedly barred from attending by the Trump administration.

Secretary of State Mike Pompeo and Defense Secretary James Mattis attended the briefing. Both have largely embraced the president's stance on the killing and have avoided pointing any fingers at Crown Prince Mohammed. Pompeo said there was no "direct reporting" that Crown Prince Mohammed ordered the hit on Khashoggi, echoing Trump's statement that "maybe he did and maybe he didn't."

Haspel ultimately briefed the Senate leadership on Khashoggi's killing on Tuesday, but a number of senators were angry about the exclusive nature of the briefing.

After Tuesday's briefing, key Republican senators said they were confident the crown prince ordered the killing and signaled they intend to push for major changes to the US-Saudi partnership. In short, Trump's position on Khashoggi has increasingly put him at odds with the GOP foreign-policy establishment.