The hiring of Miller is the latest sign that Trump’s tight-knit campaign team is expanding as he continues to lead GOP polls and planning to release more policies in the coming weeks as the primary race unfolds.

It also underscores Trump’s increasingly cozy relationship with Sessions, a prominent immigration hard-liner in Congress who has yet to endorse a candidate.

Months ago, Sessions appeared at a Trump rally in Mobile, Ala., going so far as to don a “Make America Great Again” hat. Now the aide most often at his side is joining Trump.

Miller will work alongside Sam Clovis, Trump’s national campaign co-chairman and chief policy adviser, drafting white papers and assisting the candidate with debate preparations.