WASHINGTON - The new head of the Secret Service acknowledged Tuesday that days passed before he was told about the latest allegations of misconduct at the agency, but he pleaded for patience from skeptical lawmakers calling for stronger action to restore confidence after a string of scandals.

In testimony before a House panel, Director Joseph Clancy said it was unacceptable that it took an anonymous whistle-blower for him to learn that two senior agents, allegedly under the influence of alcohol, hit a barricade with a government vehicle March 4 and disrupted an investigation on the White House grounds.

But he also sought to cast the episode as less egregious than reports have suggested, saying the agents nudged the barricade on purpose with their vehicle to move it out of the way, rather than erratically running into it. He said he was waiting to discipline the men to avoid impeding an outside probe into what happened.

"This is my first test," he said. "I'm frustrated that we can't act until we get all the facts . . . but I just don't want to act improperly too soon."

Members of both parties questioned whether Clancy was the right man for the job.

"We've got to have some changes," said House Appropriations Committee Chairman Hal Rogers (R., Ky.). ". . . I don't sense at the moment that you have the determination to make that happen."

Clancy, a 27-year veteran of the Secret Service before taking a top security job at Comcast, was named last month as the permanent head of the agency. His appearance before a House Appropriations subcommittee was the first of two on Capitol Hill this week on his agency's budget request.

Lawmakers appeared more interested in demanding answers about an embarrassing string of incidents involving agency personnel.

Clancy later met with a group of lawmakers in a closed-door briefing, and they watched the video of the barrier incident themselves.

Afterward, Rep. Jason Chaffetz (R., Utah) said, "The rate of speed of the vehicle, I think, is much slower than maybe some of the other previous news accounts would lead you to believe."

As the former head of President Obama's security detail, Clancy earned the president's trust ahead of his new post. Obama appointed him against the advice of an independent panel that recommended last fall that only an outsider could bring needed change to the agency.

The White House has said it is standing behind Clancy.