If he can accomplish this one thing, he will go down as the most powerful White House chief of staff in history.

As the new chief of staff, John Kelly has to do what Reince Priebus and a host of lawyers have not been able to accomplish over the last 6 to 7 months, and that is, curb President Trump’s Twitter habits.

To be specific, Kelly doesn’t look to stop Trump from tweeting. He doesn’t have a problem with the tweeting, itself.

Kelly’s problem is with Trump using social media as a platform to present complicated policy, 140 characters at a time. Trump has a difficult grasp on the English language to begin with. Trying to explain policy he doesn’t understand, and to do it with so few words is a headache the administration doesn’t need.

Trump’s hasty announcement a week ago, regarding a ban on transgender persons in the military set off the concern. There was no policy in place, no guidance issued, and it wasn’t an issue anyone was prepared to deal with in that moment. They were caught flat-footed.

According to a recent Politico piece, Defense Department lawyers and members of the administration knew it was an issue he wanted to address, but had warned him that it was a complicated issue with legal ramifications to consider, the response of military officials, and a host of concerns that were being analyzed at the time the president went rogue.

The administration had no plan in place, but Trump told others they would have to “get in gear” if he announced the ban first, one White House adviser who spoke to Trump said. He also said the announcement would stop the lawyers from arguing with him anymore. There is still no plan in place, and Defense Department officials have said they won’t implement the ban until guidance is given.

Get that? He’d hoped making an announcement would force them to stop analyzing and start moving.

As I’ve said before, I absolutely agree with his announcement. It’s one of those vary rare instances where I do agree with anything coming from Donald Trump, but to make such an announcement with nothing pinned down was pointless and unproductive.

One can only hope Kelly has a plan of action in place that will put a bit in Trump’s mouth (or shackles on his fingers).

According to officials from the West Wing, Kelly is planning to control what goes on Trump’s desk, will filter who gets through to the Oval Office, and who is allowed to brief him.

His goals for the tweeting are to see that the tweets move in the right direction, rather than the scattershot manner that has become the Trump trademark. Part of that is controlling who is whispering in Trump’s ear, encouraging him to broadcast his madness to the social media world.

Instead, Kelly has said he would like to know what Trump is planning to tweet before he does so and would prefer that big decisions not be announced on Twitter — but has privately conceded there will be late-night or early-morning missives he cannot review.

Kelly is trying to put together a system in which top aides don’t learn of decisions on Twitter, one where policy and personnel decisions are not first tweeted without having procedures in place to make them happen.

That’s quite the change from having people around him who are so short-sighted that they see his wild, undisciplined tweets as “shaking up” the system, rather than the chaotic reality they create.

Advisers and friends say Trump is more controlled on Twitter when he is getting good advice and has people around him he trusts — instead of people giving him false information. Several people close to him noted a spate of bad news stories Thursday, including that the special counsel had issued subpoenas and was using a grand jury in Washington, that provoked nothing overnight or in the early-morning hours, when the tweets often flow.

The bursts often come, advisers say, when Trump is frustrated with his staff or news media coverage — or just wants to buck everyone and do it his way, believing he can send the message better than anyone. Or, they say, he takes to Twitter when he wants to keep a tight circle and announce his news for fear of leaks. He also will marvel at how quickly his tweets appear on the television screen and brag about his followers.

Indeed, I expected to wake up this morning to an unhinged Twitter tirade, regarding Mueller’s grand jury, but so far, there’s nothing.

Another area where Trump’s tweets got ahead of the news?

The announcement of John Kelly as chief of staff.

Kelly already knew he had the position as chief of staff. What he wasn’t prepared for was having it announced on Twitter, moments after Priebus had been dismissed on July 28. None of the other administration officials were prepared for the news, either. They found out when their phones started going nuts.

So best of luck to John Kelly. He’s got his work cut out for him.