US House Judiciary Committee chairman Jerry Nadler told ABC political show "This Week" that Donald Trump Jr. and Allen Weisselberg, the sole trustees of The Trump Organization, were among 60 people and organizations being targeted by the probe.
"We are going to initiate investigations into abuses of power, into corruption. and into obstruction of justice", Nadler, whose committee would be responsible for starting impeachment proceedings against Trump, said. "It's our job to protect the rule of law".
During the interview, Stephanopoulos asked Nadler if he believes Trump has obstructed justice.
Nadler said it was too soon to consider whether impeachment should be pursued, however. The chairman said the threshold for impeachment is quite high, and should not be attempted unless a significant majority of the American public supports such a drastic measure.
Nadler said the Judiciary Committee will continue its probe even if special counsel Robert Mueller finds no evidence of collusion between the Trump campaign and Russian Federation.
It comes as Mr Trump attacked special counsel Robert Mueller's credibility on Saturday, disparaging former Attorney General Jeff Sessions and former FBI Director James Comey while Washington waits for Mr Mueller's report in the coming weeks.
Asked if Trump tried to obstruct justice, Nadler said, "Yes, I do".
The White House and the Trump Organization did not respond to requests for comment on Nadler's remarks.
Nadler said the committee on Monday would release the list of people and organisations it would be requesting documents from.
Testimony by former Trump lawyer Michael Cohen last week directly implicated Trump in various crimes including campaign finance violations, Nadler said.
Former White House chief of staff John Kelly and former White House counsel Don McGahn also are likely targets, he said.
Judiciary committee chairman Jerrold Nadler told ABC news that 60 individuals and entities would be receiving subpoenas from tomorrow. We will also have to look at the whole body of improper and criminal actions by the president including those campaign finance crimes to determine whether they rise to the level of removal from office, ' Schiff said.
"We do want the underlying evidence", he said.
"We're far from making decisions" about impeachment, he said. "1,100 times he referred to the Mueller investigation as a witch hunt".
"All of these have to be investigated and laid out to the American people", he added.
"We shouldn't be impeaching for a political reason, and we shouldn't avoid impeachment for a political reason", Speaker of the House Nancy Pelosi, a Democrat who represents California, told NBC News in January.
President Trump has consistently denied any wrongdoing and accused Democrats of a witch hunt.