Among the examples Metcalfe has given of alleged misbehavior: Kane's decision not to defend the state's gay marriage ban, and her decision to shut down a sting investigation that caught five Philadelphia Democrats, including four state lawmakers, on recordings accepting money or gifts.
Democrats said the proceeding was not only politically motivated but circumvented the normal process for impeachment hearings, which are rare in the Capitol.
Minutes after the hearing began, the committee's ranking Democrat, Rep. Mark Cohen (D., Phila.), asked that it be canceled.
"Impeaching for political reasons is never a good idea," Cohen said. "Using this committee and this legislature to settle political grievances is even worse."
He added: "The impeachment measure before us today is not based on any violation of law or ethics by the attorney general, but on the very political and partisan disagreements with Attorney General Kane."
When Metcalfe refused to cancel the hearing, O'Brien tried to have it postponed until early next month. Metcalfe would have none of that, and even ordered House security officers to remove O'Brien when he persisted in being heard.
O'Brien stood to go, and the rest of the Democrats left with him.
Metcalfe called the walkout "a dereliction of duty" and said that Democrats missed the chance to hear testimony about the attorney general's actions since she took office last January.
Four people testified, most focusing on Kane's decision not to defend the state in a federal lawsuit seeking to overturn Pennsylvania's gay marriage ban. That move, announced last summer, touched off a heated debate in Pennsylvania about whether the state's top lawyer was legally obligated to defend the state's laws regardless of whether she agreed with them.
"This attorney general has shown a pattern of abuse," Metcalfe told reporters after the hearing.
Kane was not invited to testify. She declined to comment.
Tuesday's hearing was a nonvoting session. It is unclear whether Metcalfe's push will ever get a committee vote, let alone a vote on the House floor. Republicans, who hold the majority in the chamber, privately say it is unlikely.