WASHINGTON ― Senate Democrats on Tuesday filibustered bipartisan foreign policy legislation dealing with several Middle Eastern countries, demanding Republicans first allow a vote on reopening the government before bringing other matters to the floor.

The move was a small example of a victory under the emerging Senate Democratic strategy, which aims to put added pressure on Senate Majority Leader Mitch McConnell (R-Ky.) to bring up House-passed appropriations bills that would reopen the government.

McConnell reiterated on Tuesday, however, that he would not allow a vote on any bill to reopen the government that does not have the support of at least 60 senators and President Donald Trump.

“The Senate will not waste floor time on show votes, messaging votes, or any other proposals which fail to check those boxes regarding the funding bill,” McConnell said on the floor.

Under the Constitution, Congress has the power to override a presidential veto on any legislation. But McConnell did not mention that on Tuesday.

Zach Gibson via Getty Images Democrats are pressuring Senate Majority Leader Mitch McConnell (R-Ky.) to bring up bills to reopen the government.

The legislative package Democrats blocked Tuesday includes security assistance to Israel and Jordan, sanctions on the Syria regime, and a measure that aims to block boycotts of Israel. Some Democrats have endorsed bills disallowing boycotts, but critics say such measures violate the First Amendment right to free speech.

In a 56-44 vote, Democrats denied the package the chamber’s required 60-vote threshold to open debate. Four Democrats joined Republicans in supporting the bill: Doug Jones of Alabama, Joe Manchin of West Virginia, Bob Menendez of New Jersey and Kyrsten Sinema of Arizona.

McConnell on Tuesday immediately moved to bring up the foreign policy bill again later this week, signaling he had no intention of backing down to the Democrats’ demands. His office also issued a press release noting that the Democratic-controlled Senate continued to pass bills amid the 2013 federal government shutdown, which was more severe and affected more workers.

It’s unclear how long Democrats can remain united in blocking legislation from coming to the floor. Whereas nearly a dozen Democratic senators have pledged to filibuster all unrelated bills ― following the urging of Sen. Chris Van Hollen (D-Md.) ― from coming to the floor, others are reserving judgment on future legislation.

“I’ve made no decision on future votes without knowing what the bills are,” Sen. Richard Blumenthal (D-Conn.) said Tuesday, adding that “there’s simply no telling” if Democrats will continue the blockade into the future.

A public lands bill that was held over from the last Congress is expected to get a vote next week, for example ― and it has support from a number of Western Democratic senators.

ALEX EDELMAN via Getty Images Senate Minority Leader Chuck Schumer (D-N.Y.)

Trump threatened last week to keep the federal government partly closed for “months or even years” if he did not get $5.7 billion for his wall at the southern border. But he is also considering declaring a national emergency with respect to the situation on the border, allowing him to direct the Department of Defense to construct the wall instead.

There was little agreement among members of his own party on Capitol Hill if he could or should bypass Congress with an emergency declaration, however.

“That’s not my preferred route. I don’t know legally if you could do that,” Sen. Lindsey Graham (R-S.C.) told reporters on Tuesday, noting that such an emergency declaration is likely to be challenged in court.

Sen. John Cornyn (R-Texas), another Trump ally in Congress, agreed.

“There’s a hard way and an easy way to do things. I think that would definitely be the hard way,” Cornyn said.

But Sen. John Kennedy (R-La.), who serves on the Senate Judiciary Committee, argued that an emergency declaration would survive legal scrutiny if Trump decides to go down that path.

“I have read the law. It would not be frivolous if he does it,” Kennedy said.