By Bo Erickson, Nandita Bose, Steve Holland and Trevor Hunnicutt

WASHINGTON, Nov 6 (Reuters) - US President Donald Trump named longtime aide Stephen Miller as his chief of staff on Friday, giving the architect of some of his toughest domestic policies one of the most powerful jobs in Washington after Republicans lost control of Congress.

Miller, who will replace Susie Wiles, assumes the role as the president prepares to confront ‌a Democratic-led House of Representatives and Senate and a wave of congressional investigations into his administration.

A longtime proponent of expansive presidential authority, Miller takes over at a moment when the Republican Party's defeat in Tuesday's ‌midterm elections could leave Trump more reliant on executive power to advance his domestic agenda.

In a social media post, Trump called Miller "one of my most trusted advisors," and praised Wiles for doing "an ou...