WASHINGTON — Democrats on the House Judiciary Committee said on Tuesday that they had retained two elite white-collar litigators and prominent legal critics of President Trump to help begin inquiries into some of the most sensitive allegations involving the president, including ethics violations, corruption and possible obstruction of justice.

The committee’s chairman, Representative Jerrold Nadler of New York, has not committed to opening a formal impeachment inquiry. But the addition of the two lawyers, Norman L. Eisen and Barry H. Berke, indicates that the Democrats do not intend to wait for the special counsel, Robert S. Mueller III, to finish his work to begin weighing issues that could ultimately be wrapped up in such a proceeding.

“The president of the United States faces numerous allegations of corruption and obstruction,” Mr. Nadler said in a statement announcing the decision. “His conduct and crude statements threaten the basic legal, ethical and constitutional norms that maintain our democratic institutions. Congress has a constitutional duty to be a check and balance against abuses of power when necessary.”

Mr. Nadler gave little detail about those inquiries in his statement, saying that Mr. Eisen and Mr. Berke would consult on matters “related to the Department of Justice, including the department’s review of Special Counsel Mueller’s investigation.” A Judiciary Committee official, who was not authorized to discuss the appointments publicly, said that Democrats would be making public more detailed plans in the coming weeks.