Elizabeth Warren on Thursday made her third trip this year to Capitol Hill to answer questions about her brainchild, the Consumer Financial Protection Bureau, which begins work in a week and still has no permanent leader in place.

For four hours — twice the allotted time — Warren answered questions as the de facto leader of the agency, accepting gushing praise of her work from Democratic members of the House Oversight and Government Reform Committee and fielding critiques from Republicans about the agency’s budget, its salaries and whether it will “kill jobs.”

The appearance followed a heated exchange in May in which Rep. Patrick T. McHenry (R-N.C.) accused Warren of lying to Congress about her role advising state attorneys general seeking a massive settlement with mortgage service providers. Warren has not denied speaking to state officials, some of whom have asked her for advice. McHenry and Warren also argued over the length of the May hearing.

Republicans have repeatedly sought to curb the powers and funding of the CFPB, which was created by a sweeping overhaul of financial regulations that became law last year.

There was still a testy tone to the proceedings Thursday. At the beginning of the hearing, Warren sat quietly as committee members squabbled over parliamentary procedure and the committee’s focus.

Reps. Elijah E. Cummings (D-Md.) and John F. Tierney (D-Mass.) pressed Chairman Darrell Issa (R-Calif.) to subpoena banks that have illegally foreclosed on the homes of U.S. soldiers fighting in Iraq and Afghanistan. Issa became confused about how the subpoenas would work, prompting Tierney to ask, “What part of the English language do you not understand?”

After 40 minutes, Warren was finally sworn in.

During the questioning, GOP lawmakers wanted to know whether the bureau’s regulations would lead to higher costs for banks. Warren said the bureau’s early work would simplify the language in mortgage documents and actually save money for banks while helping customers understand what they were signing.

Lawmakers frequently cut off her answers, prompting Rep. Jim Cooper (D-Tenn.) to criticize his colleagues’ manners.

“I didn’t vote for Dodd-Frank,” Cooper said. “But I do not want to be part of a committee . . . that treats Ms. Warren with more rudeness and disrespect than I have ever seen a committee witness treated.”

At one point, Rep. Mike Ross (R-Ark.) wanted to know whether the agency would exercise its power to ban certain financial products in its first year. When Warren said it was holding off for now, Ross slightly raised his voice, “So it would be okay then that we just revoke the power?” He quickly added: “Believe me, I’m being very respectful, ma’am. I’m from the South.”

The hearing was called “Consumer Financial Protection Efforts: Answers Needed,” but committee members did not address the critical question of who will lead the bureau.

Warren’s title for now is assistant to the president and special adviser to the Treasury secretary. Republicans have vowed to block any nomination to the top post and President Obama has not signaled who he will pick.

The agency has already hired hundreds of people but without a director in place, the CFPB will have limited ability to write consumer-protection rules, though it can enforce existing laws. Warren has said that come July 21, the bureau will be ready to be the “cop on the beat.”

“You’ve been very kind with your time and hopefully we’ve been kind back,” said Issa, more than three hours into the hearing.

“I’ve cleared my schedule, and I’m here for as long as you need,” Warren said.

“It’s still been a long day for you,” Issa replied.