If Secretary of State Rex Tillerson resigned, how would anyone know?

He has become the nation’s least influential top diplomat in recent memory. His relationship with the president of the United States is strained at best, he has no philosophy or signature initiative, he has barely staffed his own department, and he’s alienated the foreign service. The former CEO of ExxonMobil has taken one of the power positions in the U.S. government and made it an afterthought.

Who knows the truth of the NBC story that he was close to quitting last summer over clashes with President Donald Trump? But Tillerson’s strange press availability swearing his loyalty to the president is not the sort of thing loyalists usually have to do.

The secretary of state dodged questions about whether he had, indeed, as NBC reported, called Trump a “moron” — almost certainly the first time in U.S. history a Cabinet official has been asked about personally insulting the president he works for and apparently been unable, in good conscience, to deny it.

Tillerson doesn’t have an easy job. He works for a mercurial and bombastic boss who has a well-developed skill for humiliating his underlings. Even a practiced and slick diplomat — even Henry Kissinger; heck, even Cardinal Richelieu — would find the circumstances trying. But Tillerson is at sea.

He’s an accomplished man who ascended to the leadership of a quasi-state as CEO of ExxonMobil. As such, he had done plenty of work abroad. It was in business, though, not government. Making him secretary of state turns out to have been like selecting the head of the Bureau of Near Eastern Affairs to run a Fortune 500 company.

Usually establishmentarians have the advantage, if nothing else, of a great store of government experience. Brent Scowcroft devoted most of his adult life to public service; Tillerson devoted most of his adult life to ExxonMobil.

Unlike, say, James Mattis advising Trump on defense matters, this is not a professional guiding an amateur; it’s another amateur trying to school an amateur. Is it any wonder that it hasn’t gone well?

Recent Republican secretaries of state provide two models. There’s the Colin Powell approach of attending to the needs of “the building,” i.e., the civil service, and neglecting your relationship with the president. Then there’s the Condi Rice approach of tending to your relationship with the president and ignoring the building. Tillerson has done neither.

In a nationalist administration, he is a man without a country. He doesn’t have a constituency in the foreign-policy establishment, in the media, in Congress or in the bureaucracy. He and his top aides are a thin layer spread atop the org chart to little effect.

Neither of the opposing dispensations in American foreign policy should feel vested in Tillerson. If you’re a liberal internationalist who wants Trump checked, you’d prefer someone better suited to the task. If you’re a Trumpist who wants Trump empowered to transform American foreign policy, you want someone who is in sympathy with that goal.

Tillerson has been on the other side of Trump on big issues like the Paris climate accord and the Iran nuclear deal. There’s no doubt that Trump’s instincts need to be restrained and channeled. That’s different from trying to frustrate them, which is bound to run afoul of Dean Acheson’s maxim: “The most important aspect of the relationship between the president and the secretary of state is that they both understand who is president.”

Tillerson’s diplomatic skills haven’t yet been tested on anything important. At this point, he probably fails a threshold test: Can he reliably be thought to speak for the United States government?

The former ExxonMobil chief might imagine himself indispensable as a “minder” of the president. Yet Trump is now surrounded by generals who no one doubts are responsible and influential. If Tillerson left, the government would operate as before — except with a chance there’d be a secretary of state better suited to the role.

Rich Lowry can be reached via e-mail: comments.lowry@nationalreview.com.