Ms. Lerner’s lawyer, William W. Taylor III, said: “Today’s vote has nothing to do with the facts or the law. Its only purpose is to keep the baseless I.R.S. ‘conspiracy’ alive through the midterm elections.”

Republican leaders seem sensitive to that criticism, and they insisted on Wednesday that their interest lay only in exposing the truth of a large administration-led cover-up. “This is not going to be a sideshow. This is not going to be a circus,” Speaker John A. Boehner said. Then, his voice rising in anger, he went through the list of investigations that conservatives have pursued to frustratingly inconclusive ends.

“When is the administration going to tell the American people the truth? They’ve not told the truth about Benghazi, they’ve not told the truth about the I.R.S,” he said. “One would have to guess if they’re not willing to tell the American people the truth, it must not be very pretty.”

Democrats mocked their Republican colleagues. “It is a circus,” said Representative Jackie Speier of California. “Psychologists will tell you that when somebody says something is not, it clearly is.”

Before the vote on Ms. Lerner, Representative Elijah E. Cummings, Democrat of Maryland, listed what the investigation has yielded so far: $14 million spent by the I.R.S. responding to a stream of requests from Congress, and hundreds of thousands of pages of documents. “After all of that, we have not found any evidence of White House involvement,” he said. “I will not walk a path that has been treaded by Senator Joseph McCarthy.”

Republicans, however, are not the first to use the contempt process in Congress to go after opponents. In 2008 the House, then led by Democrats, held President George W. Bush’s chief of staff, Joshua B. Bolten, and his counsel, Harriet B. Miers, in contempt in connection with an investigation into whether certain Justice Department lawyers were removed for political reasons.