President Donald Trump has refused to respond to a request from Congress to provide a report determining who killed the Saudi journalist Jamal Khashoggi.
In October 2018, senators wrote a letter demanding the murder be investigated and that the White House give more information.
A Trump administration official said the president was within his rights to decline to act.
Jamal Khashoggi was killed after entering the Saudi consulate in Istanbul in October last year.
The journalist was a strong critic of the Saudi government. His body was reportedly dismembered and has still not been found.
US intelligence officials have reportedly said such an operation would have needed the approval of Crown Prince Mohammed bin Salman.
However, Saudi officials insist Jamal Khashoggi was murdered by a “rogue” team of Saudi agents not acting on the prince’s orders.
An administration statement said President Trump “maintains his discretion to decline to act on congressional committee requests when appropriate”.
However, Democratic senators told the New York Times President Trump was in breach of the so-called Magnitsky Act, which requires a response within 120 days to requests from Senate committee leaders. That deadline passed on February 8.
Secretary of State Mike Pompeo has written to Senate leaders describing actions taken against individuals.
However, the documents do not indicate who was responsible for Jamal Khashoggi’s death, as demanded by the senators.
The US has imposed sanctions on 17 Saudi officials, including Saud al-Qahtani, a former adviser to the crown prince who, it alleged, was “part of the planning and execution of the operation” that led to Jamal Khashoggi’s murder.
However, President Trump has faced criticism from senators for failing to condemn the Saudi crown prince directly.