WASHINGTON — The House Judiciary Committee on Thursday took its first vote to press forward with an impeachment investigation of President Trump, putting aside internal divisions over the process in a bid to strengthen its hand in uncovering crucial facts in the inquiry.
The measure, which was approved on Thursday morning, laid out procedures to govern the investigation and granted due process to the president. But as lawmakers began debating it early Thursday morning, the most pressing disagreement was not over specific authorities, but over whether the panel was actually engaged in an impeachment inquiry at all.
Republicans argued that no matter what Democrats on the panel contended, they simply had not crossed that threshold.
“As we say in Texas, this is fixing to be an impeachment,” said Representative Louie Gohmert, Republican of Texas. “It’s not now, but it’s fixing to be.”
Republicans were not the only ones with doubts. There is significant lingering confusion surrounding the inquiry both among moderate lawmakers who are wary of impeachment and other rank-and-file Democrats eager to begin the process who have been frustrated with the mixed signals sent by House leaders about it.
An exasperated Judiciary Committee chairman, Representative Jerrold Nadler of New York, sought to push past the debate as he opened Thursday’s hearing, insisting that semantics aside, his committee was investigating whether to impeach Mr. Trump for possible obstruction of justice, abuse of power and corruption.
“This committee is engaged in an investigation that will allow us to determine whether to recommend articles of impeachment with respect to President Trump,” Mr. Nadler said. “Some call this process an impeachment inquiry. Some call it an impeachment investigation. There is no legal difference between these terms, and I no longer care to argue about the nomenclature.”
The questions go beyond mere semantics, however. Senior Democrats and the lawyers advising them have a strong interest in demonstrating that the House is, in fact, pursuing an impeachment inquiry, which maximizes their leverage in lawsuits to compel the cooperation of witnesses and secure grand jury testimony. At the same time, Speaker Nancy Pelosi, Democrat of California, has toiled to avoid the issue, worrying that the process would be divisive, ultimately fail to result in Mr. Trump’s removal and could potentially cost Democrats in conservative-leaning districts their jobs.
The conflicting imperatives have led to an unusual process in which the Judiciary panel is going forward with what it calls an impeachment investigation without a vote of the full House.
Republicans repeatedly pointed out on Thursday that the panel had not sought or received a House vote authorizing an impeachment inquiry, as had been the case in the two modern presidential impeachments. Without it, they argued, the panel was still engaged in regular oversight. And some lawmakers suggested that the only reason Democrats had not pursued such a vote was that they lacked the necessary support in their caucus to clear the floor.
“The Judiciary Committee has become a giant Instagram filter,” said Representative Doug Collins of Georgia, the top Republican on the committee, “to make it appear that something’s happening that is not.”
At other points, though, they appeared to accept that an impeachment inquiry was underway in order to suggest changes to the resolution and charge that the Democrats were pursuing the president out of political spite.
Republicans were correct about the precedent, but Democrats argue no vote is actually necessary. Few rules govern the impeachment process, and they argue that the committee need only be considering impeachment articles to stand up an inquiry of that name.
Still, part of the confusion stems from the fact that top Democratic leaders — including Ms. Pelosi — have declined to use those shorthand terms, even as Ms. Pelosi has approved the investigative steps themselves. Instead, she has stressed the investigative work of six House committees and said only that impeachment is one possible recourse for its findings.
Things were muddled further on Wednesday when the second-ranking House Democrat, Representative Steny H. Hoyer of Maryland told reporters that the committee was decidedly not engaged in an impeachment investigation then later had to backtrack in a written statement. That statement echoed language Mr. Nadler has used in court but avoided the term impeachment investigation or inquiry.
The resolution itself under consideration on Thursday defines four authorities for the inquiry.
It would allow Mr. Nadler to designate any hearing of the full Judiciary Committee or its subcommittees as part of the investigation, a measure Democrats believe could help expedite their work by spreading it across the smaller, nimbler panels.
Under the new procedures, staff attorneys would be afforded time at each hearing to directly question witnesses. Democratic and Republican lawyers would each be given 30-minute blocks after lawmakers had exhausted their own questioning time.
The resolution also includes rules for how information collected by the committee — including classified material and grand jury secrets — will be handled. Most information will be treated as private by default, unless the chairman designates otherwise.
And for the first time, the committee’s vote would grant Mr. Trump and his legal team formal due process, by allowing his lawyers to respond to committee proceedings in writing in real time.
“No matter how we may disagree with him, President Trump is entitled to respond to the evidence in this way,” Mr. Nadler said.
But Republicans pointed out that the language falls well short of the privileges extended to the president’s legal teams in impeachment inquiries of President Richard Nixon and President Bill Clinton, where the defense was allowed to participate in all committee hearings, cross-examine witnesses and recommend witnesses for hearings.
“Not allowing the president’s counsel the same kind of rights as was done in the two previous presidential impeachments that have been put before this committee is a gross denial of due process,” said Representative Jim Sensenbrenner, Republican of Wisconsin and a former chairman of the Judiciary panel. “We are the committee that is supposed to stand up and protect the constitutional rights of everybody.”
The committee plans to put the new rules to use on Sept. 17, when Corey Lewandowski, Mr. Trump’s former campaign manager and an important witness to the special counsel’s obstruction of justice investigation, is scheduled to appear before the committee. Mr. Lewandowski was told to appear under subpoena and has indicated his willingness to come, but the White House could still try to intervene, preventing his testimony like those of past witnesses.