Washington (CNN) Transportation Security Administration Administrator David Pekoske is expected to be named acting deputy secretary at the Department of Homeland Security, according to two administration officials.

On Tuesday night, outgoing Secretary Kirstjen Nielsen announced the imminent resignation of Claire Grady, the acting deputy of Homeland Security, paving the way for President Donald Trump's pick of Kevin McAleenan to lead the department in an acting capacity. Following Nielsen's forced resignation Sunday night, Grady was statutorily next in line to become acting secretary.

"Acting Deputy Secretary Claire Grady has offered the President her resignation, effective tomorrow. For the last two years, Claire has served @DHSgov w excellence and distinction. She has been an invaluable asset to DHS -- a steady force and a knowledgeable voice," Nielsen tweeted.

With Grady's departure, DHS is changing the order of succession. The previous line of succession included deputy secretary, under secretary for management, Federal Emergency Management Administration, which does not currently have a permanent administrator, and the Cybersecurity and Infrastructure Security Agency. It's unclear what the new order is.

Pekoske was confirmed by the Senate to lead TSA in August 2017. Last year, Congress established a five-year term for the TSA administrator. Pekoske is expected to return to his role at TSA, according to a source.

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