When the White House declined to send lawyers to the first House Judiciary Committee impeachment hearing on Wednesday, top White House lawyer Pat Cipollone dismissed the day as “an academic discussion with law professors.”

While that may have been technically true, with four constitutional legal scholars as witnesses debating the standards for impeachment for eight and a half hours, the Dec. 4 hearing provided a window into what could be a pivotal debate among Democrats on how the committee decides to tackle impeachment. The day’s proceedings suggested the committee may be leaning towards making a broader case for impeachment than previously known, possibly including one or more counts of obstruction among the articles of impeachment they draft as well as evidence from Mueller’s investigation to undergird those counts.

In his opening statement, Judiciary Committee Chairman Jerrold Nadler used his first day back in the impeachment spotlight to advocate for including articles like obstruction of justice and obstruction of Congress in the potential articles of impeachment that his committee is charged with writing, noting, as he has multiple times before, that the White House’s defiance of Congress has been unprecedented. “This Committee has voted to impeach two presidents for obstructing justice,” Nadler said. “We have voted to impeach one president for obstructing a congressional investigation. To the extent that President Trump’s conduct fits these categories, there is precedent for recommending impeachment here.”

But Nadler also implied that the articles of impeachment could include some of the findings from Mueller’s investigation alongside evidence from the Ukraine scandal, noting that he believes Trump committed obstruction in both investigations. “In both cases, he got caught,” Nadler said. “And in both cases, he did everything in his power to prevent the American people from learning the truth about his conduct.”

How broadly to define the scope of the impeachment— whether to include obstruction and evidence from the Mueller investigation, or to stay focused on the whistleblower’s allegations about Trump’s conduct with Ukraine— is a crucial question for Democrats as they pursue a controversial impeachment process.

Initially, Democrats had pushed forward on a narrow impeachment focused on the question of whether Trump pressured Ukraine to investigate Joe Biden. But on Wednesday, Nadler and other Judiciary Committee Democrats signaled an openness to expanding beyond that, even as they publicly remained circumspect about moving forward with articles of impeachment at all. “We don’t know yet whether we’re going to go in that direction, but certainly there’s a case to be made that this is a pattern, and many of the things discussed in the Mueller report were part of that obstruction and part of that pattern,” Rep. Pramila Jayapal, a Democrat from Washington on the committee, told TIME. Rep. Eric Swalwell, a California Democrat on the committee, said that information from the Mueller report could be used in impeachment articles “at least to show prior conduct, like this is not an aberration.”

“Obviously as a member of judiciary who has been trying without a lot of success to get the administration to stop stonewalling our investigation, I have a deep interest in the obstruction of Congress that has occurred in connection with the Mueller report,” said Rep. Mary Gay Scanlon, the vice chair of the committee.

Other committee members who spoke with TIME Wednesday, including those who requested anonymity to advocate broadly including obstruction, acknowledged that they had not yet reached even a formal decision to draft articles of impeachment, and that speculating on their scope was premature.

Three of the legal expert witnesses testified Wednesday that they believed Trump has committed impeachable offenses; one—the lone witness called by Republicans— disagreed. Judiciary Democratic counsel Norm Eisen asked the three Democratic witnesses if they saw enough evidence to impeach Trump on obstruction of Congress, and all three said yes. “The obstruction of Congress is a problem because it undermines the basic principle of the constitution,” said Noah Feldman, a professor at Harvard Law School. “A president who will not cooperate with an impeachment inquiry is putting himself above the law.”

Eisen also asked the witnesses about obstruction of justice, relying on evidence laid out in Mueller’s report for his questioning, in another indication that the Judiciary Committee may be planning to include some of Mueller’s findings from earlier this year in its articles of impeachment. Michael Gerhardt, professor at The University of North Carolina School of Law, said the Mueller report provides “very strong evidence of obstruction of justice” and that he believes that constitutes an impeachable offense. Eisen also established a basis for other possible articles of impeachment, including abuse of power and bribery.

Jonathan Turley, professor from George Washington University Law School and the Republican witness on the panel, argued that “the record does not establish obstruction in this case.” He noted that court cases are pending over some of the Trump Administration’s privilege claims and witnesses who have refused to appear, and said waiting for a court’s decision cannot be considered obstruction. “If you make a high crime and misdemeanor out of going to the courts, it’s an abuse of power. It’s your abuse of power,” Turley told the congressional committee.

But a push to include incidents beyond Ukraine could disrupt the carefully calibrated unity the Democratic caucus is portraying. Right now, the caucus is largely united behind pushing forward with the investigation. The House Intelligence Committee’s 300-page report on its impeachment investigation released on Tuesday devoted an entire section to obstruction. But that section solely focused on the obstruction in the impeachment inquiry, which centered on whether Trump pressured Ukraine to investigate his political rival, not Mueller’s investigation. In a closed-door caucus meeting on Wednesday, Intelligence Committee Chairman Adam Schiff received a standing ovation after presenting his committee’s report, according to a senior Democratic aide, and members in the room strongly indicated they wanted to proceed with the next phase of the inquiry. But this unity only happened in the wake of the allegations about Ukraine; when the questions of impeachment were swirling around the Mueller report earlier this year, the caucus was much more divided.

While the White House did not participate in Wednesday’s hearing, White House spokeswoman Stephanie Grisham tweeted during the proceedings, calling it a “sham” and criticizing the three witnesses called by the Democrats, while praising a point Turley had made.

Turley criticized the speed and partisanship of the impeachment process, saying more witnesses and a stronger body of evidence would be necessary to move forward. “Fast and narrow is not a good case for impeachment,” Turley said.

It’s the same rationale that could be used by the Democrats when deciding whether to include obstruction and evidence from the Mueller report in their final articles of impeachment. The hearing demonstrated publicly how there is still a very live discussion happening behind closed doors. “I don’t know if it should be all inclusive, but I do think it will be hard for us not to include it at all,” Rep. Karen Bass, a California Democrat on the Judiciary Committee, told TIME. “You have the ten examples [of possible obstruction] from Mueller, should we include all of those? Should we include every time he told a witness not to come? One of the problems with this administration is there’s so much, and I think it’s extremely important to be focused.”

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Write to Tessa Berenson at tessa.berenson@time.com and Alana Abramson at Alana.Abramson@time.com.