President Donald Trump has threatened to use federal immigration officers at airports if Democrats fail to pass a bill to fund the Department of Homeland Security (DHS). This announcement comes as a partial shutdown continues to cause long lines at some of the nation's largest airports. The move is seen as an attempt to expand the type of immigration enforcement that has been a sticking point in Congress. Democrats have pledged to oppose funding for DHS unless changes are made following a controversial immigration crackdown in Minnesota. The vast majority of TSA employees are considered essential and continue to work during the funding lapse, but they are doing so without pay.