The ouster of Deputy Director Alvin “A.T.” Smith, which followed pressure from lawmakers who have called for fresh leadership at the troubled agency, came three days before he was scheduled to testify before a House oversight committee.

Smith, who had overseen the Secret Service’s day-to-day operations for the past three years, was expected to be grilled about key decisions he made regarding spending cuts and officer training — some of the issues that have been cited as contributing to recent security mistakes.

Smith, 56, has been invited to transfer to another position in the Department of Homeland Security, according to an e-mail sent early Monday to Secret Service staff that also praised Smith’s 29 years of service to the agency.

“His contributions to the Agency have been invaluable,” the Secret Service’s acting director, Joseph P. Clancy, said in a statement.

The Secret Service said Monday that its second-ranking official was resigning his post, a departure under pressure of one of the last remaining senior managers who had presided over a string of embarrassing security lapses in recent years.

The ouster of Deputy Director Alvin “A.T.” Smith, which followed pressure from lawmakers who have called for fresh leadership at the troubled agency, came three days before he was scheduled to testify before a House oversight committee.

Smith, who had overseen the Secret Service’s day-to-day operations for the past three years, was expected to be grilled about key decisions he made regarding spending cuts and officer training — some of the issues that have been cited as contributing to recent security mistakes.

Smith, 56, has been invited to transfer to another position in the Department of Homeland Security, according to an e-mail sent early Monday to Secret Service staff that also praised Smith’s 29 years of service to the agency.

“His contributions to the Agency have been invaluable,” the Secret Service’s acting director, Joseph P. Clancy, said in a statement.

Clancy, meanwhile, is lobbying to become the agency’s permanent director and remains one of the White House’s contenders for the position, according to people familiar with the deliberations who spoke on the condition of anonymity.