WASHINGTON — A group of Republican senators led by Florida Sen. Marco Rubio is pressing the Trump administration to cut off civilian nuclear talks with Saudi Arabia in the wake of journalist Jamal Khashoggi’s murder.

In a letter to President Donald Trump obtained by NBC News, five senators say they had concerns about nuclear cooperation with Saudi Arabia even before Khashoggi was killed in the Saudi Consulate in Istanbul. But they say his death has fueled further doubts about the kingdom’s leadership.

"The ongoing revelations about the murder of Saudi journalist Jamal Khashoggi, as well as certain Saudi actions related to Yemen and Lebanon, have raised further serious concerns about the transparency, accountability, and judgment of current decision makers in Saudi Arabia," the senators write. "We therefore request that you suspend any related negotiations for a U.S.-Saudi civil nuclear agreement for the foreseeable future."

The senators threatened to use an obscure provision in the Atomic Energy Act to block any U.S.-Saudi nuclear agreements if Trump does not heed their call. In addition to Rubio, the letter was signed by GOP Sens. Cory Gardner of Colorado, Rand Paul of Kentucky, Dean Heller of Nevada and Todd Young of Indiana.

Jamal Khashoggi in 2012. Ali Haider / EPA-EFE file

There was no immediate response from the White House’s National Security Council.

The Republican effort to limit U.S. cooperation with Saudi Arabia comes amid growing outrage over the killing of Khashoggi, a Washington Post columnist and Saudi citizen who wrote critically of Saudi Arabia’s government. Saudi Arabia’s government insisted for weeks that Khashoggi had left the consulate alive, then reversed course and admitted he died but said it resulted from a fistfight during a failed rendition attempt.

Last week Saudi Arabia changed its story again and acknowledged that the 15-man team sent to Istanbul had planned his killing in advance, citing information from Turkish authorities.

Bipartisan outrage has also been growing even before Khashoggi’s killing about the Saudi-led coalition fighting in Yemen’s civil war. The coalition, which still receives support from the U.S. military, has been blamed for countless deaths of civilians in bombings on peaceful gatherings as well as for contributing to the country’s harrowing humanitarian crisis.

In a sign of new willingness by Trump’s administration to challenge the Saudis on the Yemen issue, Secretary of State Mike Pompeo issued a statement late Tuesday that specifically called out the Saudi-led coalition. It said after Iran-backed Houthi rebels stop shooting missiles into Saudi Arabia and the United Arab Emirates, “coalition airstrikes must cease in all populated areas in Yemen.”

The Trump administration has been engaged in ongoing nuclear talks with Saudi Arabia all year aimed at striking a cooperation agreement, known as a “123 agreement,” that would allow U.S. companies like Westinghouse build nuclear power plants in Saudi Arabia. Billions of dollars are at stake for American companies. In February, Energy Secretary Rick Perry traveled to Riyadh to kick off the talks.

Under 123 agreements, nations can purchase nuclear technology and technical information from the United States. The United States already has a similar agreement with close Saudi ally the United Arab Emirates.

But there have been longstanding concerns about enabling the Saudis to conduct fuel-making activities that could eventually lead to the country developing nuclear weapons, fueling a nuclear arms race in the Middle East. Saudi Arabia has balked at allowing restrictions on uranium enrichment and plutonium reprocessing as part of the deal, pointing out that its archenemy — Iran — was allowed to continue some of those activities under the separate Iran nuclear deal.

Trump withdrew the U.S. from that deal earlier this year.