Former White House chief of staff John Kelly and former White House counsel Don McGahn also are likely targets, he said.
The document trawl will be used "to present the case to the American people about obstruction of justice, about corruption and abuse of power", Nadler said on ABC News' "This Week" on Sunday.
But the once trusted lawyer for the president said he did not have "direct evidence" that Trump or his campaign colluded with the Russians during the 2016 election. "I had to walk because every once in a while, you have to walk".
Fox personalities are now responding to the new Democratic investigative push, and the true dimensions of their efforts are coming into clearer focus: Precisely because Trump has committed extremely serious misconduct and wrongdoing on so many fronts, some of Fox's leading voices are resorting to portraying any and all oversight directed at the president as fundamentally illegitimate.
"Now Robert Mueller never received a vote and neither did the person who appointed him", the president said.
Trump made his remarks at the annual Conservative Political Action Conference after bringing to the stage Hayden Williams, a conservative activist who was punched at the University of California, Berkeley, last month while recruiting students for a conservative group.
The war between the two began in the 1980s, when Nadler represented the affluent Upper West Side of Manhattan in the state legislature and opposed a huge development by Trump that would transform the historic district. "[But] very little has been said about that meeting in Vietnam over North Korea or what Michael Cohen, his former fixer was saying in Congress last week".
Gergen noted that House committees "have a long history", but warned the Democrats must not "overplay their hands".
Nadler, a Democrat in the House of Representatives, will ask for documents from people with links to the White House and the Trump Organization.
President Donald Trump responded to his former personal attorney flipping on him, testifying before Congress, and working with special counsel Robert Mueller by calling the investigations into his campaign and Russian Federation "bullshit". That could alienate general election voters in key battlegrounds including Wisconsin, Michigan and Pennsylvania, which went for Democratic former President Barack Obama in 2012 but for Trump in 2016.
"I think Congressman Nadler chose to impeach the president the day the president won the election", Mr McCarthy said.
Trump lashed out at the ongoing Mueller investigation and the work behind the scenes at the Justice Department and the FBI to investigate him for connections to Russian Federation.
"The whole thing's ridiculous", Ernstmeyer said. "He talks about impeachment before he even became chairman and then he says, 'you've got to persuade people to get there.' There's nothing that the president did wrong". "But this investigation goes far beyond collusion". Comey has denied this claim.
According to a January Reuters/Ipsos poll, more than two-thirds of Republicans believe the FBI and Department of Justice "are working to delegitimize President Trump through politically motivated investigations".
Rep. Doug Collins, ranking Republican on the Judiciary Committee, said Mr. Nadler was jumping the gun.