(CNN) The House Judiciary Committee on Thursday broadened its investigation into President Donald Trump and possible obstruction of justice, authorizing subpoenas to a dozen individuals that included the President's son-in-law, Jared Kushner .

The committee also authorized subpoenas to current and former Trump administration officials related to the "zero-tolerance" immigration policy that led to the separation last year of migrant families who crossed the southern border illegally.

The vote was approved on party lines, 21-12.

Thursday's dual subpoena authorizations signal the Judiciary Committee is ratcheting up its probes into the Trump administration ahead of the panel's high-profile hearing next week with former special counsel Robert Mueller.

With the 12 subpoenas Thursday, the committee has now authorized subpoenas to 17 individuals in total. House Judiciary Chairman Jerry Nadler has issued subpoenas to three of those officials, along with subpoenas to the Justice Department for the full Mueller report and to Mueller himself to compel the special counsel's appearance next week.

At Thursday's vote, Mueller's testimony loomed over the proceedings. Many of the officials on the subpoena list are featured prominently in the special counsel's report , and Democrats say they need to speak to them as they debate whether to begin an impeachment inquiry.

At the same time, Republicans publicly aired their complaints over the planned format of the hearing, where not all members of the House Judiciary Committee will get to question Mueller next week. Several Republicans accused Nadler, a Democrat from New York, of ceding to the House Intelligence Committee when agreeing to allow 22 lawmakers on the 40-plus member Judiciary Committee to question Mueller.

"We got rolled," said Georgia Rep. Doug Collins, the top Republican on the Judiciary panel.

Nadler mostly ignored their protests at Thursday's hearing, although he did offer to "entertain any reasonable discussions" about the format of the hearing.

"I have been very lenient in permitting people to discuss the procedures at the Mueller hearing at length, which is beyond the scope of this markup. But I'm not going to comment on it further," Nadler said. He later added that the format of the Mueller hearing was "an important question," but that he was "not going to add to the diversion of attention from the two crucial subjects we have here."

The House Judiciary Committee authorized subpoenas Thursday to a number of key officials from Trump's orbit as part of its investigation into possible obstruction of justice, corruption and abuse of power: former Attorney General Jeff Sessions, former Deputy Attorney General Rod Rosenstein, former Trump Chief of Staff John Kelly and former Trump campaign manager Cory Lewandowski.

In addition, the list of potential subpoenas included David Pecker , chairman of National Enquirer parent American Media Inc., and others related to the hush-money payments made during the 2016 campaign to silence women who were alleging affairs with Trump.

The committee's subpoenas to Trump administration officials have been met so far with resistance by the White House, which has argued the officials have immunity from testifying as advisers to the President.

Trump also weighed in as Thursday's Judiciary Committee hearing got underway.

"Now the Democrats have asked to see 12 more people who have already spent hours with Robert Mueller, and spent a fortune on lawyers in so doing," he wrote as part of a series of tweets on the topic.

But the latest list of subpoena targets shows the committee is now taking a different tack by also seeking witnesses who didn't serve in the Trump administration or are outside of government altogether. Those potential witnesses wouldn't be able to rely on the same executive privilege and immunity arguments that the White House has used to direct the former Trump officials who were subpoenaed — former communications director Hope Hicks , former White House counsel Don McGahn and former deputy White House counsel Annie Donaldson — not to answer most of the committee's questions.

"There is no substitute for primary evidence as the Committee makes its decisions, which is why we have sought documents and testimony from (those officials)," Nadler said. "We will not rest until we obtain their testimony and documents so this committee and Congress can do the work the Constitution, and the American people, expect of us."

Republicans criticized the Democrats' for the latest subpoena authorizations, accusing them of trying to generate headlines. "Here we go again on another round of premature subpoena authorizations," Collins said.

In addition to the subpoenas related to the panel's obstruction investigation, the resolution approved Thursday authorized the committee to subpoena for documents and testimony related to the "zero tolerance" immigration policy, the detention of children and families and discussions of presidential pardons to Homeland Security officials.