"Secret Service has done a fantastic job from day one".
Director of the US Secret Service Randolph Alles speaks at the Justice Department previous year.
Alles' departure comes at a time of high turnover across the department which began last week when Trump withdrew his Immigration and Customs Enforcement director's nomination to stay on permanently. He expressed "regret" he was not able to address the department before the news broke.More news: Pakistan Foreign Minister's Statement Appears to Be a Call for Terror Attacks
White House spokeswoman Sarah Sanders said James Murray, a career Secret Service agent, will take over the Secret Service in May.
Just five days ago, Trump said he "could not be happier with Secret Service" following the Mar-a-Lago incident.
The president had soured on Mr. Alles a while ago, even making fun of his looks, calling him Dumbo because of his ears, two officials said.More news: WWE: Becky Lynch beats Ronda Rousey at Wrestlemania
In the unusual episode, an unauthorized woman got past security carrying Chinese passports and numerous electronic devices, including phones and a thumb drive allegedly found to contain malware.
Meanwhile, Nielsen "believed the situation was becoming untenable with the President becoming increasingly unhinged about the border crisis and making unreasonable and even impossible requests", a senior administration official tells CNN.
The Secret Service and ICE are each part of DHS. Cissna is director of USA citizenship and immigration services, which runs the legal immigration system.
Alles - a 35-year veteran of the Marines - had also had leadership posts in Customs and Border Protection and led the agency's Air and Marine Operations.More news: Brexit: UK asks European Union for further extension until June 30
The Republican president, seeking re-election in 2020, has taken a hard line on immigration since taking office in January 2017, and he has said he will make border security a central theme in next year's race.