Bullshitting is easy, but governing is hard: Trump’s bluster and bombast, so effective on the campaign trail, has backfired spectacularly in office.

As Vox’s Ezra Klein noted this week, Trump is failing on almost every front. His health care bill died — killed by his own party. His approval rating has sunk to 35 percent. His executive orders banning immigrants from seven Muslim-majority countries were struck down by the courts. Russia-related investigations are undermining his agenda. And his administration, plagued by leaks, remains divided.

There is still plenty of time for Trump to turn things around, but so far he appears hapless and lost.

To get a better sense of why Trump’s presidency has sputtered, I reached out to George C. Edwards, a professor of political science at Texas A&M and the author of On Deaf Ears: The Limits of the Bully Pulpit. Edwards is a scholar of the presidency, focusing on the links between presidential leadership and public policymaking. His view of presidential leadership is simple: Presidents have immense power, but they rarely achieve legislative success without understanding policy or persuading Congress.

Edwards has written 25 books on American politics, including Predicting the Presidency, which draws on public opinion data and case studies to analyze the persuasive powers of the presidency.

I asked him why Trump’s first 70 days in office have looked like, well, a disaster.

Here’s what he told me.

1) Trump is a strong communicator but a lousy policy specialist

First of all, the president is a public relations specialist, not a master of the material. Trump clearly doesn't understand policy or even how government operates. So he has to rely on the goodwill of the public and of Congress. But note that one of his first gestures to the House Freedom Caucus during the health care debate was a warning that he's going to come after them if they don't surrender to him — and that's to his own party. This is a bad move in any case, but it's especially bad if you don't already have the public on your side, if you don't have a mandate of some kind. Basically, Trump doesn't have any leverage; the people in Congress are often more popular in their districts than he is, and so there's no price to pay for opposing him. It's also very difficult for Trump to persuade members of Congress when he so obviously has no knowledge of the relevant issues. Even when presidents do understand policy, it's hard to persuade members of Congress. When you're both unpopular and uninformed, it's almost impossible — there is just no basis for persuasion.

2) Trump underestimated the importance of Congress

The biggest constraint on any president's legacy is typically Congress, because you need Congress for tax reform, to appropriate money, to do almost anything meaningful. And Trump seems to have no appreciation for Congress. He said, for months, that everything was going to be so easy — health care, tax reform, infrastructure, defeating ISIS. There was, apparently, no regard for the role of Congress in any of this. And now he’s learning just how significant Congress can be.

3) Trump’s decision to wage war against the bureaucracy was foolish

Trump has declared war on the bureaucracy, and that is a fundamental error in judgment. The bureaucracy is usually oriented toward giving the president what he wants. But by so aggressively working to dismantle it, he's going to receive maximum pushback (at the EPA [Environmental Protection Agency], for instance) at every step of the process. And you need the bureaucracy to come up with policy.

4) The administration is too divided and chaotic to get anything done

It's a huge deal. A chaotic, divided administration doesn't come up with policies. Dysfunction begets more dysfunction. It's pretty clear that Trump didn't have any policies or principles. He never had a tax plan or an infrastructure plan or an ISIS plan. He had vague aspirations, not policies. So on health care, for example, he was beholden to and reactive against Congress, and was selling someone else's policy, which he barely understood. This is an incredibly weak position for the president. The administration, moreover, is too busy fighting among itself to develop and pursue a coherent agenda.

5) Trump’s managerial style doesn’t translate to politics

Trump has the mentality of a businessman. He wants to tell people what to do and fire them if they don't. But government doesn't work that way, and Trump is discovering that fact.

6) Trump’s strength is his populist appeal, but presidents rarely move public opinion