Cheatle, who took responsibility and confessed to "the most significant operational failure in decades," later succumbed to the calls for resignation, which he resisted at first.
Kimberly Cheatle, the head of the US Secret Service, attended a 4-hour session of the House of Representatives Oversight Committee of the US Congress.
She testified about the assassination attempt on former President Donald Trump in Butler, Pennsylvania.
"WE FAILED"
The head of the Secret Service admitted they had failed. He also took responsibility.
Cheatle also responded to allegations that not enough resources were allocated to protect Trump. He argued that security was increased some time before the assassination attempt.
"The level of security has been steadily increasing as threats evolve," he said.
Cheatle also claimed that they met Trump's request for additional security before his Pennsylvania rally.
However, he left questions about the security plan unanswered.
He stated that the Secret Service is conducting an internal investigation on this issue.
During the session, calls for resignation came one after another from both the Democratic Party and the Republican Party.
Republican House Oversight Committee Chairman James Comer spoke harshly.
"The Secret Service has become the epitome of incompetence. "It is the most significant operational failure in decades."
"You can't stay in charge of the Secret Service when there is an assassination attempt on a presidential candidate," said Democratic Party Representative Ro Khanna.
Cheatle initially resisted calls for his resignation, saying, "I am the best person to lead the Secret Service at this time."
On July 13, Republican presidential candidate Donald Trump was assassinated in Pennsylvania, suffering an ear injury.
Cheatle resigned today, a day after the attack, MSNBC reported.