WASHINGTON – The House will vote Tuesday on a resolution that would block President Donald Trump’s national emergency along the southern border.

Trump declared a national emergency this month after Congress sent to the president a bipartisan funding bill that failed to meet his demand for $5.7 billion for a wall along the U.S.-Mexico border. Trump made the declaration to free up billions from other sources to pay for the barrier. 

Democrats have said the resolution is unconstitutional and will use a provision from the National Emergencies Act to try to halt the president.

“If the president is successful in getting his way on this, rest assured he will come back, he will try this again, probably on other issues as will future presidents. The Congress must step up,” said Rep. Joaquin Castro, the Texas Democrat leading the effort.

The move puts Republicans in an uncomfortable position because many of them urged Trump not to declare a national emergency.

House Speaker Nancy Pelosi said Monday the vote was “to defend our democracy” and she hoped Republicans would join Democrats.

“This is not about politics, it’s not about partisanship, it’s about patriotism,” the California Democrat said.

Can Congress stop the emergency declaration?

Technically, yes. If both the House and Senate were to pass the resolution and the president were to sign the bill, it would halt the national emergency. But the chances of that happening are almost nonexistent.

Trump believes declaring a national emergency is well within his constitutional rights and he has vowed “100 percent” to veto legislation if it makes it through Congress.

Both the House and Senate would then need to come up with support from two-thirds of lawmakers present to override Trump’s veto, a difficult task. As it stands, only a few Republicans have said publicly they plan to vote with Democrats on the issue.

Which Republicans have said they’ll support the measure?

The House version of the resolution had well over 200 co-sponsors Monday afternoon. Just one, Rep. Justin Amash, is Republican. His being listed as a co-sponsor is no surprise – the Michigan Republican is known for breaking with his party.

On Saturday, Amash hammered his fellow Republicans on Twitter for being hypocritical: “The same congressional Republicans who joined me in blasting Pres. Obama’s executive overreach now cry out for a king to usurp legislative powers. If your faithfulness to the Constitution depends on which party controls the White House, then you are not faithful to it.”

On Monday night, North Carolina Sen. Thom Tillis, a Republican, announced he would vote in favor of a resolution that disapproved of the national emergency in an op-ed in the Washington Post.

“As a U.S. senator, I cannot justify providing the executive with more ways to bypass Congress,” Tillis wrote. “As a conservative, I cannot endorse a precedent that I know future left-wing presidents will exploit to advance radical policies that will erode economic and individual freedoms.”

GOP Sens. Susan Collins of Maine and Lisa Murkowski of Alaska have also indicated support for the measure in its current form. 

The national emergency has been controversial for Republicans, many of whom warned the president that it could set a bad precedent. But it is unclear how many will publicly oppose the president and vote to terminate the order.

Is the resolution going to pass?

The bill is expected to breeze through the House on Tuesday and then, under terms of the act, it must be taken up by the Senate within 18 days. The resolution’s future in the Senate remains unclear.

Most legislation that comes up in the Senate requires 60 votes to pass. However, because this resolution is considered “privileged,” it needs just 51 votes, increasing the chances of passage. There are 47 Senate Democrats – none of whom have spoken against the resolution – so if the Democrats stay unified only four Republicans would need to cross party lines. Tillis, Collins and Murkowski already have said they would if the legislation remains the same as it was introduced.

Why does this resolution get special treatment?

Normally legislation comes up for a vote at the discretion of the speaker or majority leader. That means if a lawmaker introduces legislation the leadership doesn’t want to deal with, the bill may not be brought up for a vote. But because this resolution comes from the National Emergencies Act, once it is introduced it must come up for a vote.

Are there other options?

If Congress is unable to halt the national emergency through the legislative process, members could still file lawsuits, a move Pelosi did not rule out during a press conference last week.

California and 15 other states have already filed a lawsuit over the declaration, arguing it exceeds the power of the president and unconstitutionally redirects federal money that would have gone to their states.

And the liberal watchdog group Public Citizen filed a lawsuit on behalf of Texas landowners who were told their property would be seized for the wall.

Contributing: John Fritze, Alan Gomez, Christal Hayes

Donald Trump declares national emergency to free up billions of dollars for border wall

16 states sue Trump over national emergency declaration, border wall

The Wall: An in-depth examination of Donald Trump’s border wall