This throwaway line in a Washington Post article by Robert Costa about the latest split within the Donald Trump campaign over whether to flip-flop on immigration is one of the more terrifying things I’ve ever seen people inside a campaign admit about their candidate:

Trump tends to echo the words of whomever last spoke to him, making direct access to him even more valuable, the people said, requesting anonymity to talk about internal campaign discussions.

This is an absolutely terrifying trait in a potential president of the United States.

A president has to spend a lot of his time talking to people who want to persuade him of things. And many of those people disagree with each other.

This isn’t just about strategic disputes among members of the candidate’s team. Presidents have to weigh in on disputes between people on two sides of a conflict; they have to decide which countries to cultivate closer alliances with (and which can be safely ignored or antagonized).

A president whose opinion on a conflict is shaped by whichever side of the conflict he last spoke to? At best, that’s an administration where the most powerful White House official is the scheduler. Or a president who makes it clear that he can’t be trusted to do what he says — a president who loses all his power both in Congress and in diplomacy.

At worst, it’s a president who assures the doves in his Cabinet that he won’t be starting a war anytime soon, then calls in a nuclear strike after a talk with the hawks.

Trump’s advisers recognize he’s fickle — but they don’t appear to realize the implications

As I noted last week, Trump’s public agonies over what to do on his signature issue revealed his disconcerting tendency — contrary to his truth-teller, bomb-thrower image — to agree with whomever he’s speaking to.

Trump’s blithe inconsistencies, and his maddening insistence that the media is just misinterpreting what he said before, make a lot more sense if "Trump tends to echo the words of whomever last spoke to him."

Trump’s hints that he might "soften" on immigration by allowing some unauthorized immigrants to remain in the US came a few days after he met with his Hispanic advisory group, many of whom support immigration reform that legalizes unauthorized immigrants in some way.

According to Costa’s reporting, Trump’s continued twists and turns over the issue over the course of the week were the result of whom he was talking to: advisers who either wanted him to stand his ground on immigration, like campaign CEO Steve Bannon and trusted ally Jeff Sessions, or who wanted him to moderate, like campaign manager Kellyanne Conway and surrogate Rudy Giuliani.

I worry that I’m stating the obvious here about how terrible it would be if a president of the United States publicly spent a week waffling over administration policy. But whichever Trump insiders talked to the Washington Post don’t appear to have thought about that a whole lot.

To them, Trump’s utter fecklessness is an opportunity: It means that with enough "access to the candidate," you can win any dispute over policy or strategy. It certainly doesn’t appear to be a reason not to try to make this man president of the United States.

Maybe they should stop thinking about how to get access to their sheeplike, gullible candidate, and start thinking about what it would mean if they couldn’t.

Donald Trump hates lies, but can't tell the truth