When Ms. Harris then pressed Mr. Sessions on a Justice Department policy he cited as his rationale for not answering questions, Mr. McCain spoke up.
“Chairman,” Mr. McCain said, “the witness should be allowed to answer the question.”
Mr. Burr responded: “Senators will allow the chair to control the hearing. Senator Harris, let him answer.”
Several observers saw a case of sexism, and some suggested possible racial undertones.
Supporters of Ms. Harris compared the episode to the exchange last week, when Mr. Burr and Mr. McCain admonished her for not affording Mr. Rosenstein the time to answer a question.
Ms. Harris was asking whether Mr. Rosenstein would give unlimited authority to , the special counsel appointed in May to investigate possible ties between the Trump campaign and Russian officials, when Mr. Burr and Mr. McCain interjected.
“The chair is going to exercise the right to allow the witnesses to answer the question, and the committee is on notice to provide the witnesses the courtesy — which has not been extended all the way across — extend the courtesy for questions to get answered,” Mr. Burr said at the time.
Asked to comment on Tuesday’s exchanges, a spokesman for Ms. Harris pointed to her Twitter account: “It’s unacceptable that Sessions — the top law enforcement official in the country — cannot name his legal basis for evading questions,” she .
Democratic senators and left-leaning supporters have pounced on the opportunity to argue against these high-drama exchanges, often turning them into Twitter gold.
Senator Elizabeth Warren, Democrat of Massachusetts, endured the spotlight in February when she was cut off by a Republican: “Silencing @SenKamalaHarris for not being ‘courteous’ enough is just unbelievable,” last Wednesday. “Keep fighting, Kamala! #NeverthelessShePersisted”
This time, a male colleague, Senator Ron Wyden, Democrat of Oregon, spoke up.
“Again, @SenKamalaHarris was doing her job,” Mr. Wyden . “She was interrupted for asking tough questions. I was not interrupted.”
Later on Tuesday night, Ms. Harris Twitter missive: “The women of the will not be silenced when seeking the truth,” she wrote, before asking her supporters to donate.
Here is a partial transcript of Ms. Harris’s exchange with Mr. Sessions.
HARRIS: “Is that policy in writing somewhere?”
SESSIONS: “I think so.”
HARRIS: “So did you not consult it before you came before this committee knowing we would ask you questions about that?”
SESSIONS: “Well, we talked about it. The policy is based …”
HARRIS: “Did you ask that it would be shown to you?”
SESSIONS: “The policy is based on the principle that the president …”
HARRIS: “Sir, I’m not asking about the principle. I am asking, when you knew you would be asked these questions and you would rely on that policy, did you not ask your staff to show you the policy that would be the basis for you refusing to answer the majority of questions that have been asked of you?”
McCAIN: “Chairman, the witness should be allowed to answer the question.”
BURR: “Senators will allow the chair to control the hearing. Senator Harris, let him answer.”