Party leaders are exploring all of their legal and procedural options. Some, including Representative Elijah E. Cummings, the chairman of the House Committee on Oversight and Reform and also a close ally of Ms. Pelosi’s, threatened this week to withhold the salaries of federal employees who fail to appear before a House committee.

Mr. Cummings also said Democrats should consider “inherent contempt” — the congressional power, last used in the 1930s, to jail officials who defy subpoenas. Mr. Connolly, who leads an oversight subcommittee, agreed.

“We should be putting people in jail,” Mr. Connolly said…

“We can’t have mealy-mouthed language about more facts have to come in,” said Adam Green, a founder of the Progressive Change Campaign Committee, a liberal advocacy group. “We’re past that stage. People want accountability.”