The Department of Homeland Security will have to furlough some 30,000 employees if Congress doesn't reach a deal on the issue of executive immigrant amnesty and pass a bill to extend funding for the department past the end of February, DHS Secretary Jeh Johnson said Sunday on CNN.

Congress has until Feb. 27 to reach a deal, but are held up by disagreements over whether the DHS funding bill should include riders that would stop President Barack Obama's executive action plan to provide deportation amnesty to millions of illegal immigrants.

Johnson told lawmakers that it's important to keep the immigration issue separate from the funding of his department, claiming that terrorists are currently inside the United States working with the Islamic State on how to best conduct attacks, The Washington Times reported.

"This is not a situation to make light of," Johnson told CNN. "In these challenging times we need a fully funded Department of Homeland Security."

"I am on Capitol Hill now virtually every working day talking to Democrats and Republicans about the importance of a fully funded Department of Homeland Security in these times in particular," Johnson said. "Let's not forget that the Department of Homeland Security interfaces with the American public more than any other department in our government at airports and at ports."

Johnson said that the nation should have the immigration debate, but not at the expense of the safety of the American people.

"If people in Congress want to have the debate about immigration reform, let's have that debate, but don't tie that to funding public safety and Homeland Security for the American people," he said, adding that it's also unfair and ineffective to require people to work without pay.

If Congress can't reach a deal to extend funding for the department, DHS officials would implement a contingency plan that requires most of the employees who patrol the border and screen airport passengers to work without pay, according to The Wall Street Journal.

The House has already passed legislation to fund the DHS past February with provisions that seek to prevent Obama's executive action, but the bill has been blocked by Senate Democrats.

Roughly 230,000 people are currently employed by the DHS. The furloughs would primarily target administrative staff.