Stephen Miller, the 34-year-old senior policy adviser has been the driving force behind President Donald Trump's immigration reforms since 2016.

A rising star on the far right for years, Miller has been making headlines because of his polarizing demeanor and statements long before his time in the administration.

Recently he's faced calls for resignation after the Southern Poverty Law Center published emails from Miller referencing and linking to publications known for supporting white nationalist ideology.

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White House senior policy adviser Stephen Miller was on the front lines as President Donald Trump's administration butted heads with Democratic lawmakers over Trump's wishes for a $5-billion wall along the US-Mexico border.

The 34-year-old was also identified as the driving force behind the Trump administration's "zero tolerance" policy that separated migrant children from their families at the southern border.

He has been a rising star on the far right for years, often making headlines because of his polarizing demeanor and statements long before The New York Times reported that he was the origin of the controversial policy.

After Homeland Security Secretary Kirstjen Nielsen's abrupt resignation, multiple reports said Miller was behind the department's shake-up in favor of harsher border policies, a sign of his continued influence on Trump's policies.

When leaked emails showed Miller exchanging links to publications known to support white-nationalist ideology with a Breitbart editor, Miller was called a "bonafide white nationalist" and faced calls from several House committees for his resignation.

One of the few remaining staffers from Trump's 2016 campaign, Miller has also written some of the president's biggest speeches, including Trump's first State of the Union address.

Here's how Miller became Trump's right-hand policy man.