The White House has denied Committee Chairman Elijah Cummings’ request for Trump adviser Stephen Miller to testify before the House Oversight Committee, according to various media outlets.

The Trump administration sent a letter, signed by White House counsel Pat Cipollone, that said the refusal to make Miller appear before the committee stems from a “long-standing precedent” for “members of the White House staff to decline invitations to testify before congressional committees.”

Cummings invited Miller to “make his case” for President Donald Trump’s aggressive policies cracking down on both illegal and legal immigration last week.

The combative Miller is one of the White House's most conservative and influential voices in pushing moves that Trump has taken to curb immigration. He engineered Trump's Muslim travel ban and is widely viewed as the driving force behind the administration's hardest-line immigration policies.