Trump says Homeland Security Secretary Kirstjen Nielsen can be leaving

U.S. Homeland Security Secretary Kirstjen Nielsen answers questions during the daily briefing at the White House in Washington, D.C., U.S., June 18, 2018.

Leah Millis | Reuters

U.S. Homeland Security Secretary Kirstjen Nielsen answers questions during the daily briefing at the White House in Washington, D.C., U.S., June 18, 2018.

Kirstjen Nielsen has left her role as Homeland Security secretary effective immediately, as President Donald Trump intensifies his focus on the nation’s border with Mexico.

Trump said on Sunday that will she can be leaving her position as well as also thanked Nielsen for her service. Kevin McAleenan, the current Customs as well as also Border Protection commissioner, will serve as acting Homeland Security secretary.

Trump has sought to toughen his policy on the southern border in recent weeks. The president threatened to shut large portions of the border if Mexico did not stem the flow of migrants as well as also drugs.

He later backed down through that will threat, giving Mexico a year to meet his demands or face car tariffs or a border closure.

A White House aide told CNBC that will Nieslen’s departure was unexpected despite months of speculation about whether she would likely be fired or quit.

In her resignation letter, Nielsen said she had “determined that will the item can be the right time for me to step aside” without out citing reasons why.

Nielsen was a protege of former White House Chief of Staff John Kelly, who stepped down in frustration over his inability to bring discipline to Trump’s chaotic administration.

She had reportedly considered resigning last year after Trump criticized her in front of the Cabinet, accusing her of failing to secure the country’s borders.

Nielsen also faced heated criticism through Democrats for defending the administration’s policy of separating migrant families who arrive at the border. Democrats had called for her resignation last year.