White House senior adviser Stephen Miller is "singularly focused on how to get people out of the country," according to a senior Trump administration official.

The Washington Post reported on Sunday that Miller has been determined to remain the authoritative voice within the West Wing on immigration.

He's emerged as a key voice shaping the Trump administration's hardline approach.

Former and current administration officials told the Post that Miller is fixated on ramping up deportations and has developed a penchant for micromanaging agencies.

Miller convened meetings on Fridays, according to the Post, where he would "alternately scream [at], demand or encourage" lower-level employees within the Department of Homeland Security.

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White House senior adviser Stephen Miller is "singularly focused on how to get people out of the country," according to a senior Trump administration official.

The Washington Post reported on Sunday that Miller has been determined to remain the authoritative voice within the West Wing on immigration, emerging as a key voice shaping the Trump administration's hardline approach.

Former and current administration officials told the Post he's been fixated on ramping up deportations and has developed a penchant for micromanaging agencies — blindsiding cabinet leaders who found their staffers leaving the West Wing and discovering they met with Miller without their knowledge.

Read more: The Trump administration reportedly spent months trying to make sure unauthorized immigrants couldn't go to school

Miller convened meetings on Fridays, according to the Post, where he would "alternately scream [at], demand or encourage" lower-level employees within the Department of Homeland Security.

"He's always micromanaging everything we do, or trying to, without really knowing or appreciating the operational challenges," one Department of Homeland Security official told the Post.

Another senior official told the Post that Miller disdains the usual bureaucratic process, convinced "an activist judge" would halt the Trump administration's priorities in federal court.

"Stephen's argument, in a nutshell, is that you can go through the whole process, dot every i, cross every t, get thousands of comments, come up with the regulation — and we'll still get sued and an activist judge will enjoin it," the official said.

Miller has pushed President Donald Trump to embrace cultural wedge issues such as immigration, believing it will galvanize his base. Recently, he was highly influential in the administration's announcement of a new rule last week making it easier for immigrants on public assistance to be rejected for green cards. It's set to be implemented in mid-October.

Read more: The Trump administration is planning to roll out a new rule rejecting green cards for immigrants on food stamps and other public aid

Politico reported Miller sent a series of scathing emails last year berating immigration officials for not moving faster to roll out the new public charge rule, and had called their department an "embarrassment."