Sanders is expected to resign as the US government is facing criticism for the poor conditions migrant children are kept in while in US custody, the New York Times reported citing a federal official.
Sanders replaced Kevin McAleenan who was appointed acting secretary of homeland security after Kirstjen Nielsen resigned from her post.
Last week, US Health and Human Services Secretary Alex Azar urged Congress to approve emergency funding to help the agency cope with the high number of migrants apprehended at the US-Mexico border before resources are completely exhausted by July.
Azar highlighted that the rate of unaccompanied migrant children apprehended at the US-Mexico border has doubled in 2019 as compared to last year.
Caravans of migrants from Central American countries seeking asylum began to move toward the United States through Mexico last fall. Trump has called the surge of arrivals a crisis and declared a national emergency in February to secure funds to build a wall on the border with Mexico.