Washington (CNN)Every Senate Democrat voted on Tuesday to block Republicans' proposal to fund the Department of Homeland Security, which runs out of money on Feb. 27.
Democrats block funding for DHS to protect Obama immigration orders
They objected to several provisions added to the bill by House Republicans that restrict funding to implement President Barack Obama's executive orders on immigration.
On a 51 to 48 vote, the Republican majority fell shy of the 60 needed to defeat the Democratic filibuster.
Republican leaders vowed to continue debating the bill and to publicly pressure Democrats to okay the $40 billion in funding for the agency.
But Democrats, confident they have the political upper hand in the dispute, said they would hold firmly against the bill and urged Republicans to drop the immigration provisions and pass a clean bill.
Republicans are anxious to fund the agency but also need to satisfy the demands of a large bloc of House Republicans who want the bill ban the department from carrying out the President's recent immigration executive orders, which they vehemently oppose.
Democrats oppose adding what they call "poison pill' amendments to the $40 billion funding bill. With the vote on Tuesday, they want to demonstrate to Republicans, who have 54 seats in the Senate, the bill can't get the 60 votes it would need to pass with the amendments attached.
Asked before the vote if he expected his caucus to be unified, Senate Democratic Leader Harry Reid told CNN, "I expect we'll do just fine."
"We should pass a homeland security bill with no strings attached," Reid said in a speech on the Senate floor. "That's where we are going to wind up."
On Friday, Assistant Democratic Leader Dick Durbin told a conference call with the immigration reform advocacy group America's Voice that "we are united as a caucus and we're going to work to stop this [Republican] strategy."
Republican leaders on each side have refused to say what steps they would take next if Senate Democrats block the bill.
If a compromise cannot be reached before the Feb. 27 deadline when the agency runs out of money, Congress might need to resort to a continuing resolution while negotiations continue. Reid blasted that approach saying keeping DHS at current funding levels means a $1 billion reduction at a time when threats from terrorism are rising.