If there were any doubt left about the acrimony that many Republicans harbor for Elizabeth Warren and the new consumer bureau she’s shaping, it vanished Tuesday during a surprisingly hostile exchange with Rep. Patrick McHenry (R-N.C.) on Capitol Hill.

McHenry, chairman of a House oversight subcommittee, had accused Warren of misleading lawmakers earlier this year about the extent of the new Consumer Financial Protection Bureau’s role in settlement talks between the nation’s largest mortgage servicers and state and local officials, an assertion that she denied.

But the real rancor emerged about an hour into the hearing when McHenry asked Warren to stay a bit longer to field additional questions. Warren balked, saying that she already juggled her schedule to accommodate the hearing and had other appointments.

“Congressman, you are causing problems,” Warren said, chiding McHenry. “We had an agreement.”

“You had no agreement, you are making this up, Ms. Warren,” McHenry replied.

Warren leaned upright in her chair, mouth agape and speechless.

Rep. Elijah Cummings (D-Md.) quickly tried to diffuse the standoff. “Mr. Chairman... I’m trying to be cordial here, but you just accused the lady of lying,” he said.

Warren finally offered to answer any written questions that lawmakers wanted to submit, and the hearing ended.

But the unseemly episode underscored the animosity that GOP members have shown repeatedly toward the new consumer regulator, which they view as an unnecessary government overreach, as well as for Warren, who many believe would burden financial firms with onerous new rules.

For her part, Warren’s rare flash of temper came as she faces enormous pressure from House Republicans who want to scale back the power and reach of the new watchdog, and an ongoing uncertainty over whether President Obama will install her as the bureau’s first permanent director.

Senate Republicans have made clear that they would not confirm without major changes to the bureau’s structure.