WASHINGTON — The House Judiciary Committee on Thursday approved a dozen new subpoenas targeting a who’s who of witnesses cited in Robert S. Mueller III’s report as Democrats sought to elevate their showdown with President Trump over episodes of possible obstruction of justice documented by the special counsel.
The panel also approved a separate group of subpoenas seeking information about the Trump administration’s practice of separating children from their families at the border.
And House Democratic leaders set Tuesday for a full House vote to hold Attorney General William P. Barr and Commerce Secretary Wilbur Ross in contempt of Congress over their refusal to relinquish under subpoena documents related to the administration’s efforts to add a citizenship question to the 2020 census.
“The House will not shirk from its oversight of this administration and its malign effort to silence the voices of millions in our democracy,” said Representative Steny H. Hoyer of Maryland, the majority leader, referring to fears that a citizenship question would dissuade immigrants from answering the census.
Among the prominent figures to be subpoenaed by the Democrats are Jeff Sessions, the former attorney general; Rod J. Rosenstein, his deputy who appointed Mr. Mueller, the special counsel; John F. Kelly, the former White House chief of staff; Jared Kushner, the president’s son-in-law and senior adviser; and Corey Lewandowski, a former Trump campaign manager. Democrats also authorized a subpoena for David J. Pecker, who as head of American Media helped Mr. Trump during the 2016 presidential campaign buy the silence of a pornographic film actress and a former Playboy model, both of whom claimed to have had sexual relationships with him.
The committee’s actions set up a slew of possible new conflicts with the White House, which has taken a dim view of House Democrats’ continued investigation of matters studied by Mr. Mueller. White House officials could try to intervene to block testimony from many of those subpoenaed on Thursday who are current or former high-level administration officials, as they have with other witnesses.
That would only deepen the standoff between the administration and the House. On the census issue, Mr. Barr and Mr. Ross could still reach an accommodation with the House Oversight and Reform Committee, but more likely, Tuesday’s vote would allow the committee to go to court to try to pry the documents loose and make criminal referrals for Mr. Barr and Mr. Ross to the Justice Department for defying congressional subpoenas.
Despite rancorous Republican opposition, Judiciary Committee Democrats easily pushed the subpoena authorizations through on Thursday along party lines — promising to jump-start two of their highest-priority oversight investigations of Mr. Trump and his presidency. The chairman, Representative Jerrold Nadler of New York, did not indicate when he would deploy the newly authorized orders, but he is likely to wait until after closely anticipated testimony in the committee next week from Mr. Mueller himself.
The first oversight inquiry focuses on Mr. Trump’s attempts to impede federal investigators studying his campaign’s ties to Russia constituted obstruction of justice or an abuse of power.
“The committee on the judiciary has a constitutional obligation to investigate credible allegations of misconduct,” Mr. Nadler said as he opened the hearing. “There is no substitute for primary evidence as the committee makes its decisions.”
Mr. Trump fumed about the new subpoenas on Twitter Thursday morning, urging Democrats to “go back to work” on policy issues rather than trying to take additional “bites at the apple” after the conclusion of Mr. Mueller’s 22-month investigation.
Representative Doug Collins of Georgia, the top Republican on the committee, protested what he called a “subpoena binge” that was designed to provoke political conflicts rather than find information.
“Today’s subpoena binge is an effort to change the narrative,” Mr. Collins said. “It is a show of force. It is a chance for the chairman to prove to his rank and file, and the rest of the Democratic caucus, he can be tough on the Trump administration after being pushed around for six months.”
In addition to Mr. Sessions and Mr. Rosenstein, the Mueller-related subpoenas target Michael T. Flynn, Mr. Trump’s former national security adviser; Jody Hunt, Mr. Sessions’s chief of staff; Rob Porter, a former top White House aide; and Rick A. Dearborn, another former White House official. Mr. Flynn has already been subpoenaed by the House Intelligence Committee.
The immigration-related subpoenas are part of a Judiciary Committee investigation of the Trump administration’s divisive policies at the border. They specifically authorize the committee to demand testimony and documents from current and former administration officials about its so-called zero tolerance policy at the border, the practice of separating migrant families and the standards of detention of migrants.
They are also seeking information about any talk of presidential pardons for Department of Homeland Security officials involved in carrying out the president’s immigration orders, despite the possibility that some might violate existing law.
Mr. Nadler said on Thursday that he was pursuing a compulsory process because the Justice Department had failed to meaningfully comply with voluntary requests for the same information; the Homeland Security and Health and Human Services departments, he added, had largely complied with similar requests.
“We have given the administration ample time to respond to these serious reports of egregious conduct,” Mr. Nadler said. “This committee cannot sit idly by. There must be oversight and accountability.”
The immigration-related subpoenas prompted a fierce debate between Republicans and Democrats on the committee over which party was more committed to addressing the unfolding humanitarian crisis at the southern border. Several Democrats who have visited detention sites there in recent weeks vividly recalled what they saw and pleaded for the Trump administration to adopt higher standards of care, particularly for children.
Mr. Collins accused Democrats of pursuing the subpoenas merely to distract from “a very large and very public intraparty squabble over funding for the humanitarian crisis at the border” that has consumed Democrats in recent weeks after the passage of an aid bill deemed insufficient by liberals.