The Department of Homeland Security is heading for a shutdown Feb. 27 if lawmakers on Capitol Hill cannot agree on how to fund the agency that deals with counterterrorism operations.

Until Feb. 24, Republicans in both the House and Senate, including the leadership, have sought to tie a measure undoing President Obama’s executive action in immigration, which would shield millions from deportation to funding of the Department of Homeland Security.

The debate goes back to mid-December, when Congress narrowly averted a shutdown by passing a $1 trillion budget just hours before its deadline. By a narrow vote, the budget was approved, but it only funded the Department of Homeland Security for about three months, a move Republicans said would allow them time to come up with a strategy to deal with the immigration announcement from November.

The Department of Homeland Security includes immigration operations like the United States Border Patrol.

Senate Majority Leader Mitch McConnell, R-Ky., said he would separate the two issues and vote on a “clean” DHS funding bill, but would also vote on a measure to still roll back Obama’s immigration plans.

A deal looked likely as Senate Majority Leader Harry Reid, D-Nev., told reporters on Capitol Hill that an agreement “on a pathway” forward and a final vote may come as early as Thursday.

The Senate voted 98-2 to begin the debate on Feb. 25, but even if the Senate passes funding, the outcome in the House is uncertain.

“Democrats need to end their weeks-long filibuster of Homeland Security funding right now,” McConnell said on the Senate floor Feb. 25. “The dual-pronged approach I’ve outlined — allowing the Senate to stop ‘unwise and unfair’ overreach on the one hand, and to fund DHS through the fiscal year on the other — is a sensible way forward.”

Boehner faces backlash from more conservative members of the lower chamber who want the two tied together.

U.S. Rep. Steve King, R-Iowa, who represents Ames and is an outspoken opponent of illegal immigration, weighed in on social media, expressing disapproval with what was playing out.

“Senators arguing fund DHS but vote a separate bill to defund executive amnesty. Have you heard of Obama veto? Think we were born yesterday?” King tweeted.

If the deal to fund DHS without immigration actions tied to it moves through the Senate to the House, King is likely a “no” vote, tweeting, “Senators want separate bill to defund exec amnesty. Fine, when & only when Obama signs bill to defund exec amnesty, we will then fund DHS.”

The House already approved funding of DHS, but did tie it an amendment that rolls back the immigration order.

The Senate voted a total of four times before Feb. 25, all of which failed to reach a 60-vote threshold to move forward as Democrats filibustered the funding while it was tied to immigration.

House Minority Leader Nancy Pelosi, D-Calif., said Republicans in the House have no plan to keep DHS open.

“With every House Democrat cosponsoring clean DHS funding legislation, it is clear this crisis only exists because Republicans prioritize anti-immigrant extremists over the safety of the American people,” Pelosi said. “Republicans must end this madness and join Democrats to fund Homeland Security immediately.”

Even with a shutdown, almost 80 percent of DHS employees are considered “essential,” and would remain on the job without pay.

The House and Senate have until the evening of Feb. 27 to pass funding with identical language to avoid a shutdown of DHS.