Representative Jerrold Nadler, the chairman of the House Judiciary Committee, said Sunday that he planned to request documents from more than 60 people with ties to President Trump, his administration and his businesses, including the president’s eldest son, Donald Trump Jr., as part of the committee’s investigation of the president.

Using the language of a prosecutor, Mr. Nadler said his goal was to present “the case to the American people about obstruction of justice, corruption and abuse of power,” which could lay the groundwork for eventual impeachment proceedings or other congressional action. He added that it was “very clear that the president obstructed justice.”

Mr. Nadler, Democrat of New York, told ABC’s “This Week” that he would also request documents from Allen Weisselberg, the chief financial officer for the Trump Organization. Michael D. Cohen, Mr. Trump’s former personal lawyer, repeatedly referred to Mr. Weisselberg’s central role in Mr. Trump’s business transactions during his testimony before the House Committee on Oversight and Reform last week.

Mr. Nadler said Mr. Cohen “directly implicated the president in various crimes, both while seeking the office of president and while in the White House,” singling out as a particular concern Mr. Cohen’s claim that he was reimbursed for hush money payments to keep quiet Mr. Trump’s affairs.