President Trump has once again found himself at odds with Congress in his defense of a foreign leader.

Even his closest allies on Capitol Hill are preparing to blunt Trump’s avowed allegiance to Saudi Arabia by expanding sanctions on the country over the murder of journalist Jamal Khashoggi.

This wouldn’t be the first time lawmakers took international relations into their own hands after Trump refused to respond strongly to evidence of a foreign government’s malfeasance. Trump pushed back on sanctions against Russia over the nation’s meddling in the 2016 presidential election, so Congress passed them last year over his objections. Trump said then he believed Russian President Vladimir Putin when he insisted that the Kremlin was not involved in any effort to interfere in America’s politics.

Now, in the wake of Trump’s apparent absolution of Saudi Crown Prince Mohammed bin Salman in the Oct. 2 slaying of Khashoggi, a Washington Post contributing columnist, Republicans and Democrats say they are prepared to pass another set of sanctions to hold the Saudi government accountable.

Even Sen. Lindsey Graham (R-S.C.), who is known for his tough stances when it comes to foreign affairs but who is also one of Trump’s staunchest defenders on Capitol Hill, said Tuesday that sanctions on Saudi Arabia should be included in a must-pass measure to fund the government by Dec. 7. In a Twitter thread, Graham wrote that Mohammed is “beyond toxic” and that “when we lose our moral voice, we lose our strongest asset.”

Such comments were echoed by other Senate Republicans, primarily those who have frequently been critical of Trump -- notably retiring Sens. Bob Corker (Tenn.) and Jeff Flake (Ariz.) -- and do not have the ear of the president like Graham does.

“I never thought I’d see the day a White House would moonlight as a public relations firm for the Crown Prince of Saudi Arabia,” Corker, the outgoing Senate Foreign Relations Committee chairman, said on Twitter.

If Congress cannot push through more sanctions on Saudi Arabia in the lame-duck session, it may have a more challenging time doing so next year when Sen. Jim Risch (R-Idaho) likely replaces Corker at the helm of the Foreign Relations Committee. Risch is more loyal to Trump, and while he signed a bipartisan letter urging sanctions on Saudi Arabia last month, he has not said anything about Trump’s decision to give Mohammed a pass on his suspected role in Khashoggi’s death.

In a power move late Tuesday, Corker and Sen. Robert Menendez (N.J.) the top Democrat on the Foreign Relations Committee, invoked the Magnitsky Act, which requires Trump, within 120 days, to make a determination of human rights violations by a foreign leader. So essentially they are forcing him to say whether Mohammed bears any responsibility in Khashoggi’s death. (The CIA has concluded that Mohammed ordered the assassination, The Washington Post reported last week.)

In an implicit rebuke to Congress, Trump tweeted Wednesday morning: “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!”

Complicating matters is that while Russia has long been considered an adversary of the United States, Saudi Arabia is an ally. It was far easier for Republicans to pounce on Russia’s wrongdoing despite Trump’s reticence. With Saudi Arabia, economic and national security factors make them more hesitant to disrupt the U.S. relationship with the kingdom.

Which is why Congress has been slow to act on human rights atrocities against Yemeni civilians at the hands of Saudi Arabia. Now lawmakers have the death of Khashoggi to light a fire under them to act. Increasingly, they are coming to the conclusion that Saudi Arabia is not an ally after all.

The situation has the potential to create not only a major rift in the world order, but also a significant moment of tension in Trump’s relationship with congressional Republicans.

Karoun Demirjian contributed to this report.