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White House says Stephen Miller won't testify on immigration to House Oversight

(CNN) The White House has informed the House Oversight Committee that aide Stephen Miller will not testify before the panel about his role in President Donald Trump's controversial immigration policies, according to a letter obtained by CNN.

In the Wednesday letter, White House counsel Pat Cipollone says there's "long-standing precedent" for the White House to decline offers for staff to testify on Capitol Hill. Instead, the White House counsel said Cabinet secretaries and other executive branch officials would make a "reasonable accommodation" for House Oversight Chairman Elijah Cummings' questions on immigration policy.

But the move is likely only to ratchet up tensions between the White House and the Maryland Democrat after both the administration and the Trump Organization have defied three of his subpoenas this week alone -- and have pushed back against a number of his other demands.

Miller, an immigration hard-liner, has been one of the more influential voices in the White House and was seen as a driving force behind several of Trump's immigration policies, including the President's recent idea to send detained migrants to sanctuary cities largely run by Democrats.

Last year, Miller advocated for the Trump administration's "zero tolerance" policy for people illegally crossing the border into the US, which resulted in children being separated from their parents at the border, and he's been a consistent advocate of the hard-line immigration policies that have been a centerpiece of Trump's domestic agenda.

In the aftermath of news that Trump was looking to send migrants to sanctuary cities, Cummings invited Miller to testify on the administration's immigration policies on May 1. Cummings sent a letter to Miller asking him to "appear voluntarily" before the committee, and gave him until April 24 to inform the committee whether he would testify.

In the letter, Cummings said he was asking the aide to voluntarily testify because Trump had said that it was Miller who was in charge of immigration matters -- so "it makes sense for Congress to hear directly from you about how federal agencies are implementing your policies."

"I am offering you an opportunity to make your case to the Committee and the American people about why you -- and presumably President Trump -- believe it is good policy for the Trump Administration to take the actions it has," Cummings wrote.

This story has been updated.