Senate officials are demanding Donald Trump determines if Saudi Crown Prince Mohammed bin Salman played a role in murdering Jamal Khashoggi.
Republican and Democratic leaders of the senate foreign relations committee sent a letter to the president asking for a second investigation.
It comes after Mr Trump on Tuesday defended US ties with Saudi Arabia despite global condemnation over the Washington Post columnist’s killing.
The president said US intelligence agencies "continue to assess all information" but that there would be no sanctions against the Saudis following Mr Khashoggi’s murder.
Senators wrote the letter Mr Trump on Tuesday asking for a fresh investigation under the Global Magnitsky Human Rights Accountability Act.
The act requires the president to determine whether a foreign person is responsible for an extrajudicial killing, torture or other gross violation of internationally recognised human rights against an individual exercising freedom of expression.
Mr Trump earlier said the king and crown prince "vigorously deny" any knowledge of the planning and carrying out of the murder of columnist at the Saudi Consulate.
However, Mr Trump added: "It could very well be that the Crown Prince had knowledge of this tragic event. Maybe he did and maybe he didn't!"
"That being said, we may never know all of the facts surrounding the murder of Mr Jamal Khashoggi," he continued in the statement entitled "America First!"
"In any case, our relationship is with the Kingdom of Saudi Arabia. They have been a great ally in our very important fight against Iran."
The statement added that the US does not condone the killing of the columnist, but that "foolishly" cancelling 110 billion dollars in arms sales, as some in Congress have suggested, would only mean that Saudi Arabia would go to other countries to acquire them.
The statement said: "After my heavily negotiated trip to Saudi Arabia last year, the Kingdom agreed to spend and invest $450 billion in the United States. This is a record amount of money.
"It will create hundreds of thousands of jobs, tremendous economic development, and much additional wealth for the United States.
"If we foolishly cancel these contracts, Russia and China would be the enormous beneficiaries – and very happy to acquire all of this newfound business.
"It would be a wonderful gift to them directly from the United States!"
