Republican Bob Corker and Democrat Bob Menendez, the respective chairman and ranking member of the US Senate Committee on Foreign Relations, have called on President Donald Trump to determine whether or not the Saudi crown prince ordered the killing of Washington Post columnist Jamal Khashoggi.

In a pre-dawn letter to the White House on Wednesday, the senators invoked the Global Magnitsky Human Rights Accountability Act, which compels the president to “determine whether a foreign person is responsible for extrajudicial killing, torture, or other gross violation of human rights against an individual exercising freedom of expression.”

The move came in response to a Tuesday statement on Saudi Arabia by Trump, in which he railed against Iran and stressed the importance of maintaining a lucrative alliance with Saudi Arabia. The statement included multiple exaggerations and falsehoods, from the death toll in Syria to the value of confirmed Saudi arms purchases. Trump also went further than any Saudi official in defaming Khashoggi.

Most important, the president sought to play down the US Central Intelligence Agency’s reported conclusions over the powerful crown prince’s role in the killing.

“We may never know all of the facts surrounding the murder of Mr Jamal Khashoggi,” Trump said, adding: “It could very well be that the Crown Prince had knowledge of this tragic event – maybe he did and maybe he didn’t!”

The statement suggested there would be no level of culpability great enough to push Trump to endanger ties with the kingdom, days after multiple outlets reported that the CIA believed Crown Prince Mohammad bin Salman personally ordered the killing.

Senator Corker responded within hours with a new escalation, tweeting that “Maybe he did and maybe he didn’t’ won’t cut it” and announcing the invocation of the Magnitsky Act.

Trump, who one month ago accused the Organization of the Petroleum Exporting Countries (OPEC) of inflating oil prices, sang the praises of Saudi Arabia via Twitter on Wednesday.

“Oil prices getting lower. Great! Like a big Tax Cut for America and the World. Enjoy! $54, was just $82. Thank you to Saudi Arabia, but let’s go lower!”