MIAMI—Five key Republican senators are pushing President Donald Trump to take punitive actions against Saudi Arabia over the killing of dissident journalist Jamal Khashoggi, threatening to undercut ongoing nuclear negotiations with the kingdom if the president doesn’t act.

The group, led by Sen. Marco Rubio (R-FL), is pushing Trump into a corner over the U.S.-Saudi relationship by calling on the president to suspend civilian-level nuclear talks with Saudi Arabia, and warning that they might block a prospective U.S.-Saudi nuclear agreement.

“As more evidence has emerged, and certainly as the administration has become privy to more information, you’ve seen the tone and tenor of his comments change, and that’s been positive. But ultimately, while words matter, actions matter even more,” Rubio told The Daily Beast in an interview in Miami after stumping for GOP gubernatorial candidate Ron DeSantis. “The most important thing that needs to happen here is not just that the president just say the right things.”

In the days following the Saudi government’s admission that Khashoggi was murdered last month inside the kingdom’s consulate in Istanbul, the Trump administration has vowed to revoke some Saudi visas, leaving other options—including human-rights sanctions—on the table. But some lawmakers are becoming antsy as they prepare to return to Washington after next week’s midterm elections, even as Trump and Secretary of State Mike Pompeo have started to condemn the Saudi government somewhat more forcefully.

The Trump administration is seeking a deal with the Saudi government that would allow American companies to build nuclear facilities in Saudi Arabia. Lawmakers have long expressed a worry that such an agreement could pave the way for the Saudis to develop nuclear weapons themselves and those worries are growing in the wake of Khashoggi’s death.

“One of the most important things we’re doing with [Saudi Arabia] is the ability to enrich uranium and reprocess plutonium and have nuclear energy,” Rubio added. “So there’s real concern that if a government is willing to murder a U.S. green-card holder in a third country in a diplomatic facility, I think there’s a legitimate question over whether such a government could be trusted with nuclear energy and the potential weaponization of it.”

By potentially blocking a nuclear agreement with Saudi Arabia, Rubio doesn’t believe he would be undercutting the U.S. president—whom he said can send a message to the Saudi government “in a way that a senator or a member of Congress can’t.”

The Trump administration has put significant political capital into its relationship with Saudi Arabia, whose de facto leader, Crown Prince Mohammed bin Salman, has instituted some domestic democratic reforms. But lawmakers on both sides of the aisle have long been skeptical of the White House’s close relationship with the kingdom, and some say that Congress’ relationship with Saudi Arabia is the worst it has ever been—compounded by the Saudi government’s ever-changing explanations about what exactly happened to Khashoggi, a Washington Post columnist and a prominent critic of the leadership in Riyadh.

“As important as that relationship is, the price of that relationship cannot be our silence or our acquiescence when they violate norms and principles that are deeply held by the American people and that are embodied by our country,” said Rubio, who sits on the foreign relations and intelligence committees. “No relationship is too big to fail.”

Separate from the nuclear agreement, lawmakers are also threatening to use their authority to block future U.S. weapon sales to Saudi Arabia if necessary, even as Trump maintains that the arms sales are good for the American economy.

The Daily Beast reported on Wednesday that the crown prince had dispatched one of his deputies, Turki bin Faisal al-Saud, to the U.S. as part of a PR blitz to repair the kingdom’s image. The targets of the campaign include members of Congress, lobbyists, and United Nations officials.

Rubio said he was not aware of such efforts and had not been contacted by Saudi officials. But he said he would tell Turki that it “will be impossible for us to continue this alliance if that’s what they intend to continue to do,” referring to the “barbaric” operation to kill Khashoggi.