US media reported that a Department spokesperson confirmed that Wolf was sworn in as acting DHS Secretary after the Senate approved his undersecretary post in a 54-41 vote on Wednesday, reports Efe news.
Earlier this month, President Donald Trump nominated Wolf to temporarily head the DHS, without confirming whether the official will be tapped for a permanent secretary role.
"He's acting right now. We'll see where that goes," Trump told reporters on November 2.
Wolf, who previously served as Chief of Staff to former Homeland Security Secretary Kirstjen Nielsen, was appointed by Trump to the undersecretary post in February but has since been awaiting Senate confirmation.
The White House struggled to search for a DHS head after Kevin McAleenan, Wolf's immediate predecessor who also led the agency in an acting capacity, submitted his resignation to the Trump administration on October 11.
Apart from Wolf, Trump was said to have also mulled nominating Kenneth Cuccinelli, acting director of the Citizenship and Immigration Services, and Mark Morgan, acting commissioner ofCustoms and Border Protection, to fill the vacancy left by McAleenan's departure.
However, the Justice Department's Office of Legal Counsel concluded that both men were ineligible to head the DHS because they had not served at least 90 days under Nielsen, the last Senate-confirmed DHS secretary.
Created in the aftermath of the 9/11 terrorist attacks, the DHS has largely focused on federal preparations to deal with terrorism and disasters, managing border security and customs, and enforcing immigration laws.
( With inputs from IANS )