Can Donald Trump get his border wall?

U.S. President Donald Trump has been fighting to erect a physical barrier along the southern border with Mexico — a battle that has now plunged the federal government into the longest shutdown in the nation's history.

How did the U.S. get to this point, and how might it end? CBC explains.

What's the issue?

Building a border wall was Trump's signature election campaign promise, a pledge that he says is needed to stem a tide of illegal migrants and stop drug trafficking. The president is demanding $5.7 billion US to fund "steel slats or a wall," though many experts doubt such construction will have much effect.

Democrats, who now control the U.S. House of Representatives, refuse to offer more than $1.3 billion for "border security," not a wall.

The budget impasse means Congress hasn't appropriated the necessary public funds to keep the government running. The result: 800,000 federal government employees are working without pay or have been furloughed.

Why does it matter?

Put it this way: After the recent romaine lettuce scare following an E. coli outbreak, how confident do you feel about eating certain fresh greens from parts of the U.S. amid this shutdown?

Consider who isn't working right now, or working without financial relief in the U.S.

The Food and Drug Administration had scaled back inspections of high-risk foods like dairy products, fruits and vegetables. Air traffic controllers, tasked with keeping the skies safe, are probably losing sleep as they fret about their finances. And this week, 10 per cent of workers with the Transportation Security Administration called in sick.

If you're a Canadian farmer who relies on weekly reports on U.S. stats on grain stockpiles and sales metrics, you might not like the fact that the U.S. Department of Agriculture isn't putting out those reports right now.

But also think about the pain of being denied a regular paycheque. Federal workers are trying to make ends meet, lining up at food banks to feed themselves and their families.

They fear being unable to make their mortgage payments or pay to keep the lights on. They're tapping into savings and driving Ubers. According to a report by the employment website CareerBuilder, 78 per cent of Americans say they're living paycheque to paycheque.

Can this happen in Canada?

No, it shouldn't.

Budgets can fail to pass in the House of Commons. If that happens, the government would fall, said Robert Jackson, who served as a senior policy advisor to prime ministers Pierre Trudeau and John Turner. Jackson said an election would likely be called and the prime minister would ask the Governor General to dissolve Parliament. The Governor General would be expected to grant that request.

"The Canadian system operates on the basis that the executive continues no matter what," Jackson said. "It continues to be funded, the taxation system continues, money can be spent by the government using Governor General's special warrants when Parliament is dissolved, and so on."

Where is this all headed?

On Saturday, Trump pushed a new proposal to extend three years of reprieve for "Dreamers" — 700,000 undocumented immigrants brought to the U.S. as children, and shielded from deportation under the Deferred Action for Childhood Arrivals (DACA) program — in exchange for $5.7 billion US for the wall.

Democratic Speaker of the House Nancy Pelosi promptly dismissed the plan as a "non-starter." A more enticing deal would have offered permanent protections for DACA recipients.

Despite the rejection from Democrats, Republican Senate Majority Leader Mitch McConnell is expected on Thursday to take up the proposal in a Senate vote. Even if it clears the Senate, it likely will be dead on arrival in the House.

Trump has also previously threatened to invoke the emergency powers of the presidency to secure funds for the wall. He would do so by declaring a "national emergency," though constitutional scholars note that it would be difficult to make this case, given that it's not as if an overwhelming crisis critically threatening the nation's security suddenly materialized on the border.

Such a move would trigger court challenges.

The takeaway?

Trump is in a bind, and there's no resolution in sight. His popularity over the last month has dipped below 40 per cent, according to a recent NPR/PBS NewsHour/Marist poll. Immigration hardliners in his own base have complained the president is tilting towards offering "amnesty" for undocumented immigrants.

The risk for Democrats is that Trump's weekend offer could put more pressure on their party if it begins to look like Republicans are more willing to compromise. But recent polling indicates that most Americans blame Trump and the Republicans for the current stalemate, and Democrats say they won't negotiate until Trump reopens the government.

Meanwhile, hundreds of thousands of federal workers are bracing to miss another paycheque this Friday. And Trump, who said last month he would gladly own a shutdown in the name of border security, has warned this could last "months, or even years."