The Secret Service officials said, however, they will complete background checks by the end of the week, according to media reports.
The Secret Service has recently come under scrutiny after a string of high-profile security lapses, which included allowing a person with a weapon and criminal history board an elevator with US President Barack Obama, and men jumping a White House fence.
Theled to former Secret Service Director Julia Pierson's resignation in October 2014 and to the dismissal of several agency executives in January 2015.
The incidents, however, continued. On May 14, the Department of Homeland Security confirmed in a report that Secret Service supervisors Marc Connolly and George Ogilvie impaired by alcohol drove into the White House grounds on March 4, disrupting an active investigation scene.
On June 2, US government watchdog Judicial Watch said in a statement that newly released government documents confirm Secret Service chief Mark Sullivan misused agents to guard a lady friend in 2011.