(CNN) The House Judiciary Committee on Friday is moving to obtain the secret grand jury material from special counsel Robert Mueller's report in federal court, arguing they need the information in order to decide whether to impeach President Donald Trump .

The lawsuit, which was filed Friday, escalates the investigation into the President being conducted by the committee that could lead to impeachment proceedings. House Judiciary Chairman Jerry Nadler and other committee Democrats said Friday that the court filing is a new step that signals the committee is actively considering whether to introduce articles of impeachment.

The development comes as more than 100 House members have come out publicly in support of the start of an impeachment inquiry in the past few months. But counsel for House Judiciary Committee Democrats told reporters Friday that the House does not actually need to formally open an impeachment inquiry, because the committee is already investigating with the intention of determining whether to vote on impeachment articles.

"Because Department of Justice policies will not allow prosecution of a sitting president, the United States House of Representatives is the only institution of the federal government that can now hold President Trump accountable for these actions," Nadler, a New York Democrat, said at a news conference Friday, quoting from the court filing in advance of its filing.

He continued, "To do so, the House must have access to all the relevant facts and consider whether to exercise its full Article I powers, including a constitutional duty, power of the utmost gravity, a recommendation of articles of impeachment. That duty falls in the first instance to the House Committee on the Judiciary."

The court filing comes following former special counsel Robert Mueller's testimony on Wednesday, which Democrats advocating for impeachment say clearly detailed the President's criminal conduct. They said Friday that the court filing was a step toward impeachment proceedings, and Nadler said at Friday's press conference that their investigation was "in effect" an impeachment inquiry — although he noted one distinction.

"There is one difference which you could draw," Nadler said. "If you said that an impeachment inquiry is when you considering only impeachment, that's not what we're doing. We are investigating all of this and we are going to see what remedies we could recommend, including the possibility of articles of impeachment. We're not limited to that, but that's very much the possibility as a result of what we're doing."

House rules have changed

While the House voted to formally begin an impeachment inquiry the last two times Congress considered impeaching a president — Richard Nixon and Bill Clinton — the committee does not believe it needs to take such a step, the committee counsel said. That's because the House rules have changed since the Clinton impeachment to give the committee the power of subpoena and depositions already without a formal inquiry. They also argue that in other impeachment cases that haven't involved a president, the committee has not had to take the step of opening an inquiry.

The characterization of the committee counsel is a shift from how House Democrats have been speaking about the prospect of impeachment in recent months, as many House Democrats have come out in favor of opening an impeachment inquiry in order to determine how to vote on potential articles of impeachment.

The lawsuit, filed Friday in DC District Court, quotes Nadler saying that articles of impeachment "are under consideration as part of the Committee's investigation, although no final determination has been made." The language in the lawsuit was approved by House Speaker Nancy Pelosi, according to a source familiar with the matter.

"The Committee seeks key documentary evidence and intends to conduct hearings with (former White House Counsel Don) McGahn and other critical witnesses testifying to determine whether the Committee should recommend articles of impeachment against the President or any other Article I remedies, and if so, in what form," the lawsuit says.

The committee also plans to file a lawsuit early next week to enforce its subpoena of McGahn, who flouted the committee's subpoena to testify in May under direction from the White House. The two new court efforts that the House counsel add to the mounting court fights that the House is waging with the Trump administration and the President himself, most of which could ultimately become part of an impeachment case.

Republicans disputed the Democratic argument that they were entitled to grand jury materials because they were investigating to consider articles of impeachment.

"The House is either formally in impeachment proceedings, which involve both an impeachment inquiry and consideration of articles of impeachment, or we are not. It's a binary issue," said Jessica Andrews, a spokeswoman to House Judiciary ranking Republican Doug Collins of Georgia.

White House officials are brushing off the suggestion that impeachment is still on the table. The White House views this latest attempt as a strategy to keep the word impeachment afloat to appease their party, but the sense in the White House is that it's no longer viewed as a real possibility, especially following Mueller's testimony, the officials said.

Democrats fight over timing

As the number of House members calling for impeachment crosses 100, House Speaker Nancy Pelosi told members after Mueller's testimony they should say publicly what represents their districts on the impeachment questions.

Nadler, who would lead impeaching proceedings if the House pursues them, has been privately lobbying Pelosi that the House should begin an impeachment inquiry. While some Democrats saw a shift in Pelosi's comments on impeachment this week, Pelosi has nevertheless argued the House needs to obtain the information it's seeking through the courts to put together the strongest possible argument before making a decision on impeachment.

The legal process could be a lengthy one, however, in the Judiciary Committee's efforts to obtain grand jury material and McGahn's testimony.

Democrats are worried that time is running short on the window for impeachment with the 2020 campaign season around the corner, and the court cases could take weeks — if not months or years — to reach a resolution and litigate appeals.

"No I'm not trying to run out the clock. Let's get sophisticated about this, OK?" Pelosi said. "We will proceed when we have what we need to proceed, not one day sooner. And everybody has the liberty and the luxury to espouse their own position and to criticize me for trying to go down the path in the most determined positive way. Again, their advocacy for impeachment only gives me leverage."

The House is currently fighting a number of other court battles with Trump and his administration, including their efforts to obtain the President's tax returns and subpoena his banks and accounting firms.

Democrats say the grand jury material that's redacted from the Mueller report will give them the full picture of what Mueller's investigation uncovered.

Seeking grand jury material

Grand jury material is considered protected, and a court order is required to release it. Attorney General William Barr has opposed the notion of going to court to make the grand jury material public, and Republicans have accused Democrats of asking Barr to break the law when they asked him to help them obtain a court order for the release of the grand jury information.

Ahead of the lawsuit Friday, the House Judiciary Committee sent its members a memo outlining how the committee would handle and protect grand jury information.

Collins accused Democrats of "suing for grand jury material to which they have no right."

"The D.C. Circuit Court reaffirmed earlier this year that judges lack the authority to make exceptions to the rules authorizing access to grand jury material," the Georgia Republican said. "Democrats want to convince their base they're still wedded to impeachment even after this week's hearing, but a baseless legal claim is an odd way to show that."

Democrats argue they are entitled to the grand jury material because the law allows a judge to share grand information "preliminary to or in connection with a judicial proceeding." Nadler has said that his committee's investigation should apply because it's being conducted to determine whether to begin an impeachment inquiry, which is considered a judicial proceeding.

But the courts may be skeptical of that argument short of the House actually entering into a judicial proceeding, which is one of the arguments Nadler has privately made to Pelosi to begin an inquiry, CNN has previously reported.

The committee wants McGahn's testimony to help them detail what Mueller uncovered in his obstruction investigation, but he ignored their subpoena and did not appear at a May hearing under direction from the White House.

The White House has claimed that McGahn has "absolute immunity" from testifying before Congress as a senior adviser to the President, an executive privilege claim that Democrats have rejected.

The House voted in May to authorize the court battle against McGahn rather than moving to hold him in contempt of Congress for violating the subpoena.

This story has been updated with additional developments Friday.