U.S. Senate Democrats blocked Tuesday a $39.7 billion funding bill for the Department of Homeland Security. The 51-48 vote killed House-passed proposals to undo President Barack Obama's executive actions on immigration, Politico reported. There are just three weeks remaining for Obama and congressional Republicans to hammer out a compromise that funds the agency in charge of protecting U.S. residents from terrorist attacks and regulating immigration, among other functions. DHS only recently emerged as a wedge issue to between the White House and the GOP, whose members want to defund parts of the agency that would carry out Obama’s plan to defer deportation for several million undocumented immigrants.

The department will run out of money after Feb. 27, Reuters reported, but the agency would continue its national security functions. Obama, in a cabinet meeting on Tuesday, warned that inaction would endanger the paychecks of front-line federal workers in the agency formed as a response to the Sept. 11, 2001 terror attacks in New York and Washington.

Homeland Security is made up of 22 different federal departments and agencies that were streamlined to control immigration at the country’s ports and borders and to defend against and respond to terrorist attacks. The agency also manages federal response to man-made and natural disasters. In 2002, after Congress passed the Homeland Security Act, the department became its own, cabinet-level entity. It officially opened its doors on March 1, 2003, according to the DHS website, and soon absorbed the functions of the immigration and naturalization services. Those services were divided into two subagencies, the U.S. Immigration and Customs Enforcement and U.S. Citizenship and Immigration Services.

The Federal Emergency Management Agency is also under DHS. Famously criticized for its response to Hurricane Katrina in 2005, FEMA absorbed the functions of four other disaster response offices. In 2005, DHS began the first of a few rounds of reorganization to further streamline its functions. Today, the DHS boasts a more than 240,000 person work force and had a budget of $39.2 billion for the fiscal year 2014. The president requested $38.2 billion for 2015.

The U.S. House of Representatives last month passed a separate Homeland Security bill that funds everything except the executive actions on immigration. House Speaker John Boehner, a Republican from Ohio, urged the Republican-controlled Senate to pass the measure ahead of Tuesday's vote.

But Democrats stood with Obama who, in his cabinet meeting on Tuesday, stressed the potential risks of sending thousands of national security personnel to work without pay. “I talked about this yesterday [and] I want to re-emphasize it today: The Department of Homeland Security contains numerous agencies that, every single day, are keeping the American people safe,” Obama said at the top of the meeting, according to a White House pool report. “[The employees] need certainty in order to do their jobs. The notion that we would risk the effectiveness of the department that is charged with preventing terrorism and patrolling our borders, making sure the American people are safe makes absolutely no sense.”