Stephen Miller attends a Cabinet meeting at the White House on Jan. 2. (Evan Vucci/AP)
Opinion writer

When are Democrats going to try to summon Stephen Miller to Capitol Hill and grill him under oath about his direct role in so much of the chaos, incompetence and increasingly malevolent extremism gripping the Trump administration right now?

Miller, as the chief architect of President Trump’s immigration agenda, is a key figure behind Trump’s ongoing purge of the Department of Homeland Security and the president’s related embrace of ever-more cruel and radical policies. Miller’s views drew fresh scrutiny when Rep. Ilhan Omar (D-Minn.) tweeted that Miller is a “white nationalist” whose “influence on policy and political appointments” remains an “outrage.”

But, while Miller’s worldview has obviously been important in shaping Trump’s policies, his influence should be understood in another way, too: He is one of the leading figures pushing the Trump administration toward increasing venality, corruption and lawlessness.

Remarkable new revelations underscore this point — and the need for a tough Democratic reaction to it.

The Post reports that White House officials “tried to pressure U.S. immigration authorities” to release detained immigrants into “sanctuary cities” to “retaliate” against Trump’s “political adversaries.”

Relying on internal emails and interviews with administration sources, Rachael Bade and Nick Miroff report that administration officials twice proposed transporting people detained by Immigration and Customs Enforcement into sanctuary cities.

While these officials claimed this would ostensibly help deal with detention constraints, they expressly considered releasing them into House Speaker Nancy Pelosi’s district in California and into other Democratic strongholds. According to one DHS official. the rationale was “retaliation” against Democrats who at the time were resisting more money for ICE detention beds.

But senior ICE lawyers advised that this would have no legal basis. The acting deputy director of ICE told the White House that “paying to transport aliens to another location to release them” would not be a “justified expenditure.”

You’ll be shocked to hear that Miller was apparently involved in this affair. The Post reports that Miller “discussed the proposal with ICE.” As one congressional investigator who spoke to a whistle-blower revealing the scheme notes: “It was basically an idea that Miller wanted that nobody else wanted to carry out.”

The problem with this ugly scheme, obviously, is the use of migrants and the wielding of their fates as political tools — the idea that they can just be dumped anywhere for the express purpose of pressuring public officials from the opposing party to do Trump’s bidding. The presumption that this would pressure them is itself deeply problematic. Then there’s the proposed use of public resources for this purpose, which is arguably corrupt and legally dubious.

Miller’s involvement in the DHS purge

This type of flouting of the law and unbridled contempt for basic governing procedure has also saturated Trump’s ongoing purge of DHS. According to multiple reports, one key reason Trump grew enraged with DHS secretary Kirstjen Nielsen, and ousted her, was that she would not break the law at his command by shutting down the border to asylum seekers entirely.

Miller has been deeply involved in all of this. Politico reports that Miller has personally pressured numerous officials at agencies to do more to stem the influx of migrants, in what one official described as “intimidation.” It seems plausible that, at a minimum, Miller may have egged on Trump to push Nielsen to break the law by banning asylum-seekers.

Miller should face deeper and tougher scrutiny from House Democrats about his involvement in all of it. They can hold hearings and demand that he testify — which could shed light on both Trump’s efforts to flout the law and on the colossal mess Trump is making of border policy right now.

“That would absolutely be a good use of congressional resources,” Josh Chafetz, a professor at Cornell Law School who wrote a fine book on Congress’s hidden powers, told me. Chafetz added that this is particularly urgent, given that in this “central area of policy for the administration,” many of the initiatives “seem to be coming directly from the White House.”

Chafetz said the White House would assert executive privilege to keep Miller from testifying, but that the House shouldn’t accept it. “There’s no reason Congress shouldn’t learn what’s going on with the formulation of immigration policy,” Chafetz said. “If Miller refuses to testify, they should hold him in contempt.” Chafetz suggested threatening to defund Miller’s salary to compel his testimony.

Beyond accountability?

Miller has been deeply involved in Trump’s most consequential and disastrous decisions, sometimes in highly questionable ways. He helped orchestrate the slapdash rollout of Trump’s thinly veiled Muslim ban, which proceeded despite two DHS analyses undercutting its rationale. Miller intervened to bury internal data showing refugees are a net economic positive. Miller played a major role in pushing forward Trump’s horrific family separations, despite internal warnings that they would traumatize migrant children.

Yet we face a basic problem here. Positions like that of Miller — powerful but murkily defined White House advisory roles that don’t require Senate confirmation — tend to be beyond basic scrutiny and accountability.

“Miller is effectively in charge of DHS,” Douglas Rivlin, the communications director at America’s Voice, told me. “If he’s running the show and pressuring agencies to take outlandish or illegal actions, he ought to face the same oversight that Cabinet secretaries face.”

Democrats should use every single tool at their disposal to try to hold these people accountable.

Read more:

Jennifer Rubin: A new low: Trump tried to use migrants as cannon fodder against Democrats

Max Boot: End the charade. Appoint Stephen Miller to run DHS.

Greg Sargent: For Trump, the cruelty is the point. But it’s actually worse than that.

The Post’s View: Kirstjen Nielsen’s season of cruelty and futility

Jennifer Rubin: Kirstjen Nielsen’s legacy of cruelty and incompetence is sealed

Laura Bush: Separating children from their parents at the border ‘breaks my heart’