Washington (CNN) Treasury Secretary Steven Mnuchin ended a long day of testimony before House lawmakers in a verbal sparring match with California Rep. Maxine Waters, the top Democrat on the House Financial Services Committee, over his insistence on leaving for a previously scheduled appointment.

The Treasury secretary at 5:08 p.m. ET interrupted the question-and-answer session with lawmakers to remind the committee of their agreement that he would be able to leave at 5 p.m.

Mnuchin said he was scheduled to meet with a senior official from the government of Bahrain to discuss efforts to combat counterterrorism financing, but would be willing to stay until 5:15 and return at a later date to testify before the committee.

"It will be embarrassing if I keep this person waiting for a long period of time," Mnuchin said.

Waters responded: "Unfortunately, we are all pressed for time."

Read More