President Trump departs the White House with son-in-law and senior adviser Jared Kushner. (Win Mcnamee/Getty Images)

As the White House reboots for Trump 2.0 after a largely unsuccessful first two months, one lesson should be obvious: The radical, polarizing politics of the campaign trail don’t work well in governing the country.

The United States isn’t Russia or the Philippines. Our system has speed bumps, carefully constructed by our founders. Presidents don’t rule simply by executive order. They must shape policies that are comprehensible to the public and can be enacted into law.

In President Trump’s first months in office, he too often behaved as an insurgent and disrupter, rather than a chief executive. He paid a severe price, seeing the collapse of his health-care legislation and, in a Gallup tracking poll this week, receiving the lowest approval ratings for any modern president so early in his term.

There are some signs that Trump’s inner circle gets it. On foreign policy, plans are being assembled carefully as part of a broad national-security strategy. Before making big announcements on North Korea, China, Russia and the Middle East, officials want to see how the pieces fit. Trade policy, now under the supervision of Commerce Secretary Wilbur Ross, looks less crazily destructive than it initially did. Similar coordination is badly needed on tax policy.

The biggest danger to Trump 2.0 is the president’s own impulsive, embattled style — which shows most clearly in his handling of the FBI and congressional investigations of Russia’s covert action to influence the U.S. election. The best course for Trump (and our system) is for the White House to cooperate with the inquiry, let it run its course — and, meanwhile, concentrate on doing the public’s business.

(Peter Stevenson/The Washington Post)

Weirdly, Trump continues to do the opposite. He’s still arguing the discredited, bogus issue of President Barack Obama’s supposed wiretaps on Trump Tower. And he’s coyly dealing with House Intelligence Committee Chairman Devin Nunes (R-Calif.) to foster this distraction.

The Trump-Nunes allegation seems to have morphed into a contention that Trump associates were picked up incidentally in lawful foreign-intelligence intercepts of others, but that their names weren’t properly masked (or “minimized,” in the jargon) in subsequent intelligence reports that were then disseminated and leaked.

This may satisfy Trump’s desire for a counterpunch. But does any reasonable person really believe that this technical legal issue is more important than whether Trump associates cooperated in a Russian covert action against the United States, which is what FBI Director James B. Comey has said the bureau is investigating?

A better approach for dealing with the inquiry was shown this week by Jared Kushner, Trump’s son-in-law and perhaps now his most important adviser. Kushner’s Russia problem was that he met after the election not just with Ambassador Sergey Kislyak but also with a Russian banker named Sergey Gorkov, who was prepared to act as an intermediary to President Vladimir Putin. Did Kushner blame leaks, or Nazi-like behavior in the intelligence agencies? No, he agreed to testify to Senate investigators about the meetings.

The message is that Kushner thinks he did nothing wrong and has nothing to hide. One assumes he will tell the Senate that he wanted to explore opening a discreet channel to Putin, similar to those he established with numerous other global leaders during the transition. But after the secretary of state nomination went to Rex Tillerson, a genuine friend of Putin, Kushner apparently concluded Trump didn’t need any such back channel. We’ll see if that’s the whole story, but cooperating with the Senate investigation is the right start.

Kushner is apprenticing for the role of Trump’s Henry Kissinger. He’s the secret emissary, the evaluator of talent, the whisperer of confidential advice. He’s the only person in this White House who Trump can’t fire, really. All these qualities strike me as beneficial, so long as Kushner uses them to make Trump a better president who learns how to compromise and govern.

Trump’s problem is that he’s used to operating a family business, where people such as his daughter and son-in-law and a few hired guns are the only operatives he needs and trusts. He doesn’t seem to understand that he runs a public company now. His stockholders are the American people. He has disclosure requirements. He has fiduciary responsibilities.

If this were a business-school case study, a smart Wharton student would say that the chief executive needs a strong board of directors who can use his best talents but keep him from damaging the enterprise or the public that owns it.

Running a public company in this prudent way is not a choice for the chief executive, it’s an obligation. Any machinations to avoid possible legal problems are cause for dismissal. Sorry, but that’s the deal.

Read more from David Ignatius’s archive, follow him on Twitter or subscribe to his updates on Facebook.