CNN —  

As Donald Trump pursues a purge of the Department of Homeland Security amid what he is promising will be a tougher immigration policy, attention has, again, turned to Stephen Miller – one of the President’s top aides. Miller is one of the youngest and least high-profile members of Trump’s inner circle, but on immigration has long been a leading advocate of a strong hand as it relates to the handling of undocumented immigrants trying to enter the United States.

To get a fuller perspective on Miller and his influence on the President, I reached out to CNN White House correspondent – and rabid Alabama fan! – Kaitlan Collins. Our conversation, conducted via email and lightly edited for flow, is below.

Cillizza: What is the key to Miller’s success – and longevity – in this White House and with this President?

Collins: Our reporting shows Miller has already had a lot of success in serving the President. He’s become one of the President’s closest advisers, and while he may not be victorious with everything he pushes, he certainly has Trump’s ear when it comes to immigration.

Take for example what happened last week: Ron Vitiello was well on his way to becoming the director of Immigration and Customs Enforcement when Miller went to the President and told him Vitiello wasn’t in favor of him closing the southern border, as Trump had threatened to do for a week. Miller knew how the President would react to this. The White House quickly pulled the nomination – so quickly that DHS officials thought it was a clerical error until Friday morning. The Homeland Security secretary was never officially informed about the withdrawal. And [Wisconsin Sen.] Ron Johnson, a Republican who chairs the Homeland Security panel, said he was “completely surprised” by it.

The episode was revealing of Miller’s influence.

Cillizza: Miller is much lower-profile than people like, say, Kellyanne Conway or Mick Mulvaney. Is that by choice?

Collins: Very much so. Miller has made few television appearances, and my reporting shows that the low public profile is on purpose. He has a large presence inside the West Wing, but is someone who prefers to operate under the radar rather than in a public way.

Miller is someone who wants to be involved in a lot of things, just not always with his fingerprints on it.

Cillizza: How much of Miller’s views on immigration are his own and how much is he channeling what he knows Trump wants?

Collins: I think the mistake that gets made when talking about this is that people assume all of the immigration pushes coming out of the White House are masterminded by Miller. Yes, he carries significant weight in this department and can help put the President’s ideas in motion. But a lot of it comes from Trump himself.

The President’s thoughts on immigration are not new.

For example, it was the President’s idea to close the border. He kept pushing it despite advisers like Kirstjen Nielsen telling him it was a bad idea with severe consequences. So other aides, like Miller and Mulvaney, were on the other side of things, brainstorming how he could close the border without devastating the US economy. Maybe he couldn’t seal the entire border, but he could close certain ports of entry, stall some trade or slow walk entries into the US, they suggested.

Cillizza: What is the general view of Miller inside the White House (aside from Trump)? Do Ivanka Trump and Jared Kushner like him? Mulvaney?

Collins: Miller is quite well-liked inside the West Wing. He has been here since the beginning, which can’t be said for a lot of people anymore, and is seen as someone who is trustworthy.

He often gets the description of the lone wolf pushing Trump’s most extreme immigration proposals, but it’s more complicated than that. Kushner has recently become more involved on immigration talks. Mulvaney has his hand in things too, telling the President that closing the border could appeal to his base. And Trump listens to a lot of outside advice, too.

Now, Miller being liked outside of the West Wing is a different story. He’s rankled a slew of officials at Department of Homeland Security because he has often acted as if he can overrule them since the early days of the Trump White House. In a normal administration, that might not work. In this one, sometimes it does.