Senate Democrats blocked a bipartisan foreign policy bill on Tuesday as they deploy hardball tactics to try to break the shutdown stalemate.

Senators voted 56-44 to get the legislation over a first procedural hurdle, where it needed 60 votes.

Democratic Sens. Doug Jones (Ala.), Joe Manchin (W.Va.), Bob Menendez (D-N.J.) and Kyrsten Sinema (Ariz.) voted to advance it. Senate Majority Leader Mitch McConnell (R-Ky.) voted against the legislation, a procedural move that will allow him to bring the bill back up.

The legislation, which includes sanctions against the Syrian government and bolsters U.S. support for Israel and Jordan, was expected to strike a bipartisan note amid a deeply partisan shutdown fight when Republicans scheduled it last week.

But a growing number of Democrats signaled they would vote against advancing the bill, arguing the chamber should be focused on getting an agreement to end the partial shutdown, which is currently on its 18th day.

Democratic Sens. Ben Cardin (Md.), Chris Van Hollen (Md.), Tim Kaine (Va.) and Mark Warner (Va.), whose two states have large populations of federal employees, sent their colleagues a letter urging them to vote against taking up the foreign policy bill because of the shutdown fight.

"We write to urge you to join us in voting against the motion to proceed on Tuesday evening because the Senate should vote on the House-passed appropriations bills as its first order of business," they wrote.

Senate Democrats are in the minority, but if they are able to unite 41 of their 47 members behind the strategy they can grind the Senate to a standstill in an effort to ratchet up pressure on McConnell, who has refused to take up any government funding bill not supported by the president.

The escalation of shutdown tactics comes as recent talks appeared to go nowhere. In a sign of digging in, Trump is giving a prime-time address before traveling to the border Thursday, which would be the 20th day of the shutdown.

Trump has held firm in his demand for more than $5 billion for the wall. He'll also have lunch with Senate Republicans on Wednesday before congressional leadership goes to the White House for talks.

The Democratic-led House, meanwhile, is expected to begin passing individual appropriations bills this week, a move aimed at pressuring McConnell and vulnerable GOP incumbents up for reelection in 2020.

McConnell ripped Democrats earlier Tuesday over their decision to block the foreign policy bill, arguing they were throwing a "tantrum."

"Now they're threatening to shut the Senate down, too. ... They're threatening to shut down efforts to protect our allies and strengthen our relationship with Israel, something they all recently claim to support," McConnell said from the Senate floor