In an interview with Fox News, Donald Trump accidentally told the truth. Speaking to Fox Business Network’s Trish Regan, he said, “Saudi Arabia has been a great ally to me.”

In this one phrase, he revealed not only how he views the world and what is most important to him, but he also illustrated one of the most important things he has in common with Saudi Crown Prince Mohammed bin Salman—a shared profound misconception about U.S. foreign policy.

Trump’s comment is more than just a reflection of his famous narcissism. It goes deeper than thinking everything is about him. It also speaks to the only calculus he uses in presidential decision making: weighing the what’s-in-it-for-him factor.

Repeatedly throughout Trump’s career, Saudis have stepped up to help him when he needed it—buying his yacht, spending (according to his own campaign speeches) tens or even hundreds of millions of dollars on Trump products, and helping him out of debt crunches. The Saudis took an entire floor in Trump Tower, held government events at the Trump Hotel in Washington and, when he made his first trip abroad as president, projected gargantuan images of him on buildings and welcomed him like a king.

While Trump argues that he does not wish to upset the vitally important economic relationship we have with Saudi Arabia by punishing the Saudis for their apparent role in the murder of Washington Post columnist Jamal Khashoggi, his arguments about the importance of the economic ties between the two nations are overstated.

He says the Saudis have promised to buy $110 billion in arms from us. Since they made that promise they have made solid commitments for just about a tenth of that. (We should also note that the promise is less than the $150 billion promised to Barack Obama.)

He also said they committed to buy $450 billion in U.S. goods in the biggest such commitment “in the history of the world.” First, he inflated their promise. Further, the promise they did make was spread out over a decade…and would require the Saudis to increase their annual purchases from the U.S. by 150 percent a year for every year of that decade to hit their goal. There is no evidence they will do that.

“ Trump, regardless of how he acts, already has an inkling that this election could have existential consequences for his presidency and certainly major implications for how he can conduct foreign policy. ”

In fact, Saudi Arabia is our No. 22 trading partner. Its total goods imports from the U.S. are about $16 billion a year. We actually have a trade deficit with the Saudis. In other words, our trading relationship with them is better for them than it is for us.

So while the president talks about the vital nature of U.S. economic ties with the Saudis, not only is he exaggerating those ties, but the importance of the Saudis to the U.S. has fallen dramatically since the discovery of new oil deposits in the U.S. made us much less dependent on foreign suppliers. We are now the No 1 oil-producing nation on the planet.

In sum, the Saudi relationship with Trump has been significant. The Saudi relationship with the U.S., while important, is not what the president has touted it to be.

What appears to matter most here are Trump’s finances more than America’s finances.

Similarly, Trump has repeatedly shown great fondness for foreign leaders—even despots and known murderers, human rights abusers and criminals—who have treated him with deference, and especially those who have celebrated him and his family as the Saudis have done. Conversely, when leaders get tough with him, even when they are associated with our most important allies, like Germany or France or Canada, each far more important than Saudi Arabia, he has no hesitation in attacking them and putting the relationships at risk.

In other words, he really does think what matters is the Saudi relationship with him rather than with the United States. It is a view that monarchs like King Salman and his son, the crown prince, share. They are their governments. Their views are all that matters in terms of any interaction their government may have with the outside world.

Unfortunately, for both Trump and the Saudis, and fortunately for all the rest of us, that is not how foreign policy works in a democracy. While the Constitution gives wide latitude to the chief executive in the conduct of foreign policy, the Congress of the United States has great power when it comes to funding or de-funding programs, imposing sanctions or conducting investigations. Congress can largely shut down or severely impede a president’s initiatives if it so chooses. And Congress is of course chosen—as all of our House and a third of our Senate will be in less than three weeks—by the people.

Already, it is clear there is a big rift between Trump and many key members of Congress on the Khashoggi matter. What is more, in a real rarity these days, it is bipartisan, an issue that unites Republicans from Lindsey Graham and Marco Rubio to Democrats like Chris Murphy and Chuck Schumer.

Moreover, if Democrats win the House in November, we will see the emergence of a new foreign policy stance on the Middle East, in which the Khashoggi murder will only be one of the drivers that will almost certainly make life much tougher for the Saudis… and for Trump if he tries to continue as he has.

Trump, regardless of how he acts, already has an inkling that this election could have existential consequences for his presidency and certainly major implications for how he can conduct foreign policy. It is not clear Mohammed bin Salman does as well. His viability as a ruler may be severely hampered should it be the bipartisan conclusion of the U.S. Congress that he is a murderer and a liar and the opposite of the reformer he once tried to peddle himself as.

Horse racing has been referred to as the sport of kings. In some parts of the world, foreign policy is as well. But that is not the case in the United States of America. And it appears that, outraged by the brutal, brazen slaughter of a peaceful man who sought only to promote free expression, Jamal Khashoggi, the people of the United States are about to demonstrate that to both their president and his clients overseas.