But the sweeping document requests also raised immediate questions about House Democrats' strategy for probing the Administration.
The inquiries touched on everything from the President's business dealings with Russia to multiple controversies regarding the firing of former FBI Director James Comey and hush payments made to women.
Many of those very issues are already being looked at by Special Counsel Robert Mueller and prosecutors in the Southern District of New York - not to mention other committees in the House.
House Democrats also appear to be grappling with a question of whether to focus their energy on Trump's actions as president, or probe alleged past misdeeds before he ran for office, too.
Judiciary Committee staff argue there is a constitutional question about whether the party can hold the President accountable for any illicit or morally questionable activities Trump may have committed before he became president.
While extremely broad, Nadler's inquiry focuses on abuse of power, public corruption and obstruction of justice since Trump became president, though some of the inquiries also deal with the campaign and the presidential transition.
At an event at the White House with the North Dakota State championship football team, Trump was asked if he plans to cooperate.
"I cooperate all the time with everybody," he said, adding: "You know the beautiful thing - no collusion. It's all a hoax."
Those receiving letters from the House Judiciary Committee include the President's two eldest sons, Donald Trump jnr and Eric Trump; his son-in-law, Jared Kushner; his former personal secretary Rhona Graff; Allen Weisselberg, the chief financial officer of the Trump Organisation; and former top White House aides Hope Hicks, Sean Spicer and Steve Bannon.
Other demands for documents are directed to institutions including the White House, the Justice Department, the Trump campaign, the Trump transition team and the Trump Organisation.
White House press secretary Sarah Sanders acknowledged receipt of Nadler's letter and said officials "will review it and respond at the appropriate time." She did not comment further.
Recipients have two weeks to comply with the requests. Should they not do so, the Judiciary Committee will subpoena the documents, panel staff members told reporters.
Trump and Republicans have pushed back, arguing Democrats are on a fishing expedition designed to undermine the President and cripple his re-election effort ahead of 2020.
During a two-hour, campaign-style speech at the Conservative Political Action Conference, Trump mocked Democrats for the scope of their investigations.
"[T]hey don't have anything with Russia. There's no collusion," Trump said. "So now they go and morph into, 'Let's inspect every deal he's ever done. We're going to go into his finances. We're going to check his deals.' . . . These people are sick. They're sick . . . Where did that come from?"
The committee also said today's tranche of requests would not be the last, suggesting investigations by House Democrats could become broader still with time. The panel says it will seek not only Mueller's final report but also documents used in the grand jury.
Nadler's request is significant not only because he is seeking an expansive amount of material but because his committee has jurisdiction over impeachment. Any hearings exploring whether Trump committed "high crimes and misdemeanors" would take place before the panel.
The panel is seeking communications between former White House counsel Donald McGahn and the President relating to Michael Flynn, Trump's fired national security adviser, as well as Flynn's statements to the FBI about contacts with Sergey Kislyak, then Russia's ambassador to Washington.
Nadler is also seeking to learn about communications regarding Trump's firing of Comey as FBI Director, as well as what occurred at a June 2016 meeting at Trump Tower in New York. That meeting included Trump jnr Kushner, then-campaign manager Paul Manafort and Russian lawyer Natalia Veselnitskaya, who had "dirt" to offer about Democratic presidential nominee Hillary Clinton, according to an email that was made public.
Nadler has also asked American Media Inc. and its chief executive, David Pecker, a longtime Trump ally, about hush payments or "any payment" that Michael Cohen, then Trump's personal lawyer, made to assist Trump during the campaign.
The documents Nadler requested are a first step in the committee's effort to explore possible obstruction of justice by the President in connection with Mueller's investigation of Russian interference in the 2016 campaign and whether Trump or anyone close to him coordinated with the Russians during the campaign.
The committee staff coordinated the document request with Mueller's office, federal prosecutors in Manhattan (SDNY) and other committees conducting their own investigations, a House counsel said.
Committee counsel said the chairman is requesting materials that in many cases already have been furnished to Mueller or federal prosecutors in Manhattan or to other congressional panels. Many of the recipients' lawyers have already been contacted and are expected to provide the materials, the counsel said.
Though the document demands are sweeping and appear to track over Mueller's probe, a committee counsel said the panel's jurisdiction squarely covers obstruction of justice and abuse of power issues.
The House Intelligence panel, by contrast, is investigating Russian interference and counterintelligence matters, the counsel noted. But there inevitably will be some overlap. And Judiciary will share documents it receives with other committees, the counsel said.
Aides said the panel is exploring two other broad issues: public corruption and abuse of power.
The investigation of public corruption includes potential violations of the emoluments clause of the Constitution, which prohibits presidents from accepting gifts from foreign states, as well as possible campaign finance violations. Potential abuses of power include attacks on the news media and the judiciary, and the use of presidential pardon power, Judiciary Committee aides said.
Nadler's requests come as House Democrats are ramping up numerous investigations of the president, their first steps in a months-long effort that could lead to impeachment proceedings.
The House Oversight and Reform Committee received testimony from Cohen last week in a high-profile hearing where he accused Trump of lying to the public about his business interests in Russia, his role in silencing women who alleged sexual encounters during the 2016 campaign and his knowledge of WikiLeaks's hacked material that was damaging to Clinton.
The oversight panel also has given the White House until Tuesday to respond to document requests surrounding its clearance process, some of which panel Democrats have been seeking for months.
The latest letter followed news that Trump had personally instructed his then-Chief of Staff John Kelly to give Kushner a security clearance.
At the same time, the House Ways and Means Committee has created a framework for requesting Trump's tax returns. Although the tax panel has not asked for the documents yet, lawyers for the committee have instructed other panels to help make the case to the public about why the forms are essential to investigating the President.
