WASHINGTON, DC - AUGUST 22:  President Donald Trump listens to the opening prayer during Air Force Technical Sergeant John Chapman's Medal of Honor ceremony at the White House  August 22, 2018 in Washington, DC. Chapman was killed March 4, 2002 during a battle in Afghanistan. After his helicopter came under heavy fire and crashed, Chapman and other team members returned to the snow-capped mountain to rescue a stranded service member.  (Photo by Chip Somodevilla/Getty Images)
Chip Somodevilla/Getty Images
WASHINGTON, DC - AUGUST 22: President Donald Trump listens to the opening prayer during Air Force Technical Sergeant John Chapman's Medal of Honor ceremony at the White House August 22, 2018 in Washington, DC. Chapman was killed March 4, 2002 during a battle in Afghanistan. After his helicopter came under heavy fire and crashed, Chapman and other team members returned to the snow-capped mountain to rescue a stranded service member. (Photo by Chip Somodevilla/Getty Images)
Now playing
02:05
House Dems move forward with impeachment probe
Rep. Marjorie Taylor Greene (R-GA) speaks during a press conference outside the U.S. Capitol on February 5, 2021 in Washington, DC. The House voted 230 to 199 on Friday evening to remove Rep. Marjorie Taylor Greene (R-GA) from committee assignments over her remarks about QAnon and other conspiracy theories.
Drew Angerer/Getty Images
Rep. Marjorie Taylor Greene (R-GA) speaks during a press conference outside the U.S. Capitol on February 5, 2021 in Washington, DC. The House voted 230 to 199 on Friday evening to remove Rep. Marjorie Taylor Greene (R-GA) from committee assignments over her remarks about QAnon and other conspiracy theories.
Now playing
03:20
Marjorie Taylor Greene lashes out at media after backlash over controversial caucus
AP
Now playing
03:16
Maxine Waters: Jim Jordan is a bully and I shut him down
US Representative Marjorie Taylor Greene, Republican of Georgia, leaves her office on Capitol Hill on February 4, 2021 in Washington, DC.
NICHOLAS KAMM/AFP/Getty Images
US Representative Marjorie Taylor Greene, Republican of Georgia, leaves her office on Capitol Hill on February 4, 2021 in Washington, DC.
Now playing
03:51
Marjorie Taylor Greene launching 'America First' caucus
US President Joe Biden delivers remarks on Russia at the White House in Washington, DC on April 15, 2021. - The United States announced sanctions and the expulsion of 10 Russian diplomats Thursday in retaliation for what Washington says is the Kremlin's US election interference, a massive cyberattack and other hostile activity.
JIM WATSON/AFP/Getty Images
US President Joe Biden delivers remarks on Russia at the White House in Washington, DC on April 15, 2021. - The United States announced sanctions and the expulsion of 10 Russian diplomats Thursday in retaliation for what Washington says is the Kremlin's US election interference, a massive cyberattack and other hostile activity.
Now playing
02:22
White House backtracks on refugees decision after criticism
Biden speaks from the Treaty Room in the White House on April 14, 2021 in Washington, DC.
Andrew Harnik/Pool/Getty Images
Biden speaks from the Treaty Room in the White House on April 14, 2021 in Washington, DC.
Now playing
02:44
'National embarrassment': Biden reacts to mass shootings
MOSCOW, RUSSIA - APRIL 15:  Russian President Vladimir Putin (L) talks to talks to Foreign Minister Sergey Lavrov during a meeting with Uzbekistan President Islam Karimov in the Kremlin on April 15, 2013 in in Moscow, Russia. Karimov is on a state visit to Russia. (Photo by Sasha Mordovets/Getty Images)
Sasha Mordovets/Getty Images
MOSCOW, RUSSIA - APRIL 15: Russian President Vladimir Putin (L) talks to talks to Foreign Minister Sergey Lavrov during a meeting with Uzbekistan President Islam Karimov in the Kremlin on April 15, 2013 in in Moscow, Russia. Karimov is on a state visit to Russia. (Photo by Sasha Mordovets/Getty Images)
Now playing
02:07
Russia to expel 10 US diplomats in 'tit-for-tat response' to Biden sanctions
Now playing
03:10
Avlon: Here's what we know 100 days since the Capitol riot
A Russian flag flies next to the US embassy building in Moscow on October 22, 2018. - US national security advisor John Bolton is in Moscow holding meetings with senior Russian officials following Washington's weekend announcement of withdrawal from the Cold War-era Intermediate-Range Nuclear Forces Treaty, known as the INF. (Photo by Mladen ANTONOV / AFP)        (Photo credit should read MLADEN ANTONOV/AFP via Getty Images)
Mladen Antonov/AFP/Getty Images
A Russian flag flies next to the US embassy building in Moscow on October 22, 2018. - US national security advisor John Bolton is in Moscow holding meetings with senior Russian officials following Washington's weekend announcement of withdrawal from the Cold War-era Intermediate-Range Nuclear Forces Treaty, known as the INF. (Photo by Mladen ANTONOV / AFP) (Photo credit should read MLADEN ANTONOV/AFP via Getty Images)
Now playing
02:17
Political scientist: US-Russia relations are in the toilet
WASHINGTON, DC - JUNE 13: Rep. Michelle Lujan Grisham (D-NM) speaks during a news conference on immigration to condemn the Trump Administration's "zero tolerance" immigration policy, outside the US Capitol on June 13, 2018 in Washington, DC. (Photo by Toya Sarno Jordan/Getty Images)
Toya Sarno Jordan/Getty Images
WASHINGTON, DC - JUNE 13: Rep. Michelle Lujan Grisham (D-NM) speaks during a news conference on immigration to condemn the Trump Administration's "zero tolerance" immigration policy, outside the US Capitol on June 13, 2018 in Washington, DC. (Photo by Toya Sarno Jordan/Getty Images)
Now playing
02:39
Governor settles with former campaign staffer who accused her of sexual mistreatment
pool/cnn
Now playing
01:56
Hear what Dr. Gupta said when Cruz went maskless before
Now playing
02:30
Biden's decision to withdraw from Afghanistan is personal for this lawmaker
President Joe Biden speaks from the Treaty Room in the White House on Wednesday, April 14, 2021, about the withdrawal of the remainder of U.S. troops from Afghanistan.=
Andrew Harnik/AP
President Joe Biden speaks from the Treaty Room in the White House on Wednesday, April 14, 2021, about the withdrawal of the remainder of U.S. troops from Afghanistan.=
Now playing
02:10
Why Biden made his Afghanistan announcement in this particular room
U.S. President Joe Biden speaks from the Treaty Room in the White House about the withdrawal of U.S. troops from Afghanistan on April 14, 2021 in Washington, DC. President Biden announced his plans to pull all remaining U.S. troops out of Afghanistan by September 11, 2021 in a final step towards ending America's longest war.
Andrew Harnik/Pool/Getty Images
U.S. President Joe Biden speaks from the Treaty Room in the White House about the withdrawal of U.S. troops from Afghanistan on April 14, 2021 in Washington, DC. President Biden announced his plans to pull all remaining U.S. troops out of Afghanistan by September 11, 2021 in a final step towards ending America's longest war.
Now playing
01:03
Biden: It's time to end the forever war
Kinzinger
CNN
Kinzinger
Now playing
05:56
What Republican lawmaker fears after US troops leave Afghanistan
Rep. Matt Gaetz, R-Fla., questions witnesses during a House Armed Services Committee hearing on Capitol Hill, Wednesday, April 14, 2021, in Washington.
Manuel Balce Ceneta/AP
Rep. Matt Gaetz, R-Fla., questions witnesses during a House Armed Services Committee hearing on Capitol Hill, Wednesday, April 14, 2021, in Washington.
Now playing
02:59
Women detail late-night parties with Gaetz
(CNN) —  

The House Judiciary Committee on Thursday approved a resolution defining the rules of the panel’s impeachment investigation, the first vote the committee has taken related to the potential impeachment of President Donald Trump.

The party-line vote came as House Democrats have struggled to define the committee’s probe, with Judiciary Chairman Jerry Nadler saying the committee is conducting an impeachment inquiry, while House Speaker Nancy Pelosi and other Democratic leaders are refraining from calling it that.

Thursday’s vote, which does not need to be approved by the full House, gives Nadler the ability to deem committee hearings as impeachment hearings. It allows staff to question witnesses at those hearings for an hour after members conclude, gives the President’s lawyers the ability to respond in writing to public testimony and allows the committee to collect information in a closed setting.

But the dissonant messages over the probe have prompted frustration among rank-and-file members, particularly those in competitive races wary of impeachment, and it even led to the House’s No. 2 Democrat walking back his statement on the committee’s investigation on Wednesday. At her weekly news conference Thursday, Pelosi once again declined to say the committee was conducting an impeachment investigation, which happened minutes after the committee adopted its resolution stating that’s what it was in fact doing.

Nadler sought to clarify the committee’s intentions in his opening statement at Thursday’s committee meeting, acknowledging there was confusion but arguing that the language used to describe the investigation wasn’t the important point.

“This Committee is engaged in an investigation that will allow us to determine whether to recommend articles of impeachment with respect to President Trump. 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 New York Democrat said. “But let me clear up any remaining doubt: The conduct under investigation poses a threat to our democracy. We have an obligation to respond to this threat. And we are doing so.”

But Georgia Rep. Doug Collins, the top Republican on the Judiciary Committee, charged that the committee had become “a giant Instagram filter” — that Democrats were trying to dress up what they were really doing to make it look better. He argued that the Democratic resolution was “not anything special” because it grants the chairman powers that he already has access to.

“The difference between formal impeachment proceedings and what we’re doing today is a world apart no matter what the chairman just said,” Collins said, adding later, “The chairman can do this at any time, because he wants the appearance of something that it’s not. You’re not in an impeachment inquiry.”

After the committee vote, Collins accused Democrats of “trying to cover” for their moderate members by not voting in the full House to formally establish an impeachment inquiry.

Nadler vows ‘aggressive series of hearings’

The committee’s new procedures for its hearings could be on display as soon as next week, when former Trump campaign manager Corey Lewandowski is scheduled to appear on Tuesday. The committee in July subpoenaed Lewandowski and former White House aides Rick Dearborn and Rob Porter to testify on Tuesday, but it’s not clear if the White House will direct Dearborn and Porter not to appear, making the same immunity claims it has with former White House counsel Don McGahn and others.

Nadler vowed an “aggressive series of hearings” under the committee’s procedures approved on Thursday.

“The investigation will go well beyond the four corners of the Mueller report, and we will be starting with a first hearing on September 17th, we expect among others, we expect Mr. Lewandowski to testify,” he said.

Former Trump campaign manager Corey Lewandowski is seen leaving the House Intelligence Committee in March 2018 at the U.S. Capitol in Washington, DC. (Photo by Tasos Katopodis/Getty Images)
Tasos Katopodis/Getty Images
Former Trump campaign manager Corey Lewandowski is seen leaving the House Intelligence Committee in March 2018 at the U.S. Capitol in Washington, DC. (Photo by Tasos Katopodis/Getty Images)

Nadler and committee members say that adopting the resolution will make their investigation more effective as they gather information – through subpoenas, hearings and the courts – to decide whether to introduce articles of impeachment against the President.

But the broader question – is the committee conducting an impeachment inquiry? – has flustered Democrats all week.

To Nadler and many on the committee, the committee is conducting an impeachment investigation. They argue that the debate over how to label the investigation is merely semantics: they have stated publicly and in court filings that their investigation is part of an active effort to decide whether to pursue impeachment.

House leaders’ different approach

House leadership, however, has taken a different tack. Pelosi and Majority Leader Steny Hoyer have declined this week to say affirmatively that the committee’s investigation was an impeachment investigation or an im