At the center of the longest government shutdown in American history was a wall – that is, some sort of barrier along the 1,954 mile border between the U.S. and Mexico, intended to stop the influx of illegal migrants crossing illegally. The president made building the wall a centerpiece of his 2016 campaign, and has continued to advocate enthusiastically for its construction.

Both Republicans and Democrats are feeling pressure to set out their visions for border security, and to say whether or not those visions include a wall. Here’s a look at what both sides are saying.

“Building a wall is the best way to secure the southern border.”

The idea of a physical barrier is not a new one. Our border with Mexico already has about 700 miles of wall and fencing in areas where there are dense populations or no natural barriers.

The president’s repeated call for a border wall has become a rallying cry among people who think it’s the best way to curb illegal border crossings. According to a recent survey from the Pew Research Center, roughly 40 percent of Americans – and 80 percent of Republicans and Republican-leaning independents – support expanding the existing wall, which is an all-time high. Many of them believe that a physical barrier would signify a tough new approach to illegal border crossing.

For some wall supporters, reports of caravans heading to the border from Central America gave new urgency to the cause. Others have argued that the European nations that welcomed migrants with open arms are now facing domestic unrest and negative economic consequences. And for others, including people who believe that we need legal immigration for continued prosperity, it still represents a common-sense way to limit illegal migration. As one columnist notes, “[i]f people want to come from Latin America to the US…then they should come here legally.”

“We should pursue other, more effective ways to secure the southern border.”

The simplest argument against building an expanded wall is it won’t work. Rep. Henry Cuellar, whose Texas district borders Mexico, says that walls are ineffective. “We already have permanent walls and fences in the highest traffic areas – and they have proven to be unsuccessful. Between 2010 and 2015, the current 654-mile pedestrian wall was breached 9,287 times,” he wrote in an op-ed. Cuellar instead recommends the use of more modern technology, increased border personnel, and better coordination with Mexican law enforcement to patrol the border and pursue organized crime.

Rep. William Hurd, a former CIA officer and current member of the House Committee on Homeland Security, says that “when it comes to the border, we’ve allowed an outdated, physical barrier to dominate the national dialogue and stifle innovation.” Instead, he suggests a “Smart Wall,” which would use sensor, radar, and surveillance technology, in combination with machine-learning artificial intelligence (AI), to assist border patrol personnel. No Labels details a number of high-tech tools here.

Others suggest that because many people cross the border illegally in search of work, issuing more work visas would encourage more people to cross legally. At the same time, enforcing penalties on employers who hire undocumented workers would be an effective way to reduce illegal border crossings.

As our founder wrote in a recent op-ed, we must move beyond rhetoric and have an honest conversation about what it takes to secure the border.