Karen Tumulty: No, President Trump. Reagan didn’t try to build a wall.

FILE - In this May 24, 1985, file photo, then U.S. President Ronald Reagan works at his desk in the oval office of the White House as he prepares a speech on tax revision. (AP Photo/Scott Stewart, File)

When you are a conservative losing an argument, say it was what Ronald Reagan would have done.

President Donald Trump was the latest Republican to try that familiar gambit, with a tweet Thursday morning that claimed his border wall would be the culmination of what Reagan tried and failed to achieve:

"Even President Ronald Reagan tried for 8 years to build a Border Wall, or Fence, and was unable to do so. Others also have tried. We will get it done, one way or the other!," Trump tweeted.

Chalk up another lie. In fact, Reagan thought a barrier on the border was a terrible idea. He was asked about illegal immigration during an April 1980 Republican primary debate with George H.W. Bush. This was a debate in Texas, no less, where voters were more sensitive than most to border issues. The answer, he argued, was more migration, not less.

“Rather than ... talking about putting up a fence, why don’t we work out some recognition of our mutual problems and make it possible for them to come here legally, with a work permit, and then while they are working and earning here, they pay taxes here?” Reagan asked. “And when they want to go back, they can go back, and they can cross. And open the border both ways, by understanding their problems — this is the safety valve right now they have with that unemployment.”

The 40th president would work diligently over the next six years for a major overhaul of the nation's immigration laws. He considered the Immigration Reform and Control Act of 1986 a significant part of his legacy. Yet today, in the interest of pushing the buttons of the GOP base, even his own son misrepresents what it was meant to do, and how events played out:

"Hey @POTUS in 1986 my father made a deal with the Democrats Amnesty for Border Security my father is still waiting. U have no choice its now or never," Michael Reagan tweeted.

While it is true the act produced the largest legalization program in history, that was precisely what it was intended to do. To Reagan, "amnesty" was not a dirty word. "I believe in the idea of amnesty for those who have put down roots and who have lived here, even though some time back, they may have entered illegally," Reagan said during a 1984 presidential debate.

Where the act fell short — no doubt in Reagan’s eyes, as well as those of pretty much everyone else of both parties who supported it — was in its enforcement provisions. While it did call for tightening security, its chief mechanism for cutting down on illegal immigration was a provision that, for the first time, made it illegal for an employer to knowingly hire a worker who was not in the country legally. Reagan and the drafters of the legislation recognized that barriers at the border mean nothing so long as the magnet of economic opportunity is drawing migrants to this country.

That was the most contentious element in the act, and the biggest hurdle to its passage. Until then, harboring an illegal immigrant had been a felony, but the 1952 "Texas Proviso" stated that hiring one didn't violate the law. Under the 1986 law, employers can face civil penalties of $250 to $10,000 for each of those employees.

What never materialized was any realistic means of enforcing the new requirements for employers. In hiring, they often just look the other way at workers they have reason to believe are in the country illegally, for which they are rarely punished. This month, an undocumented housekeeper who was literally making Trump's bed at his New Jersey country club told the New York Times that the president's own businesses have been lax in assuring that their workers are in this country legally.

Both parties have been guilty of not cracking down on employers who flout the law. "There are never enough federal budget resources," its chief authors, former congressman Romano Mazzoli, D-Ky., and former senator Alan Simpson, R-Wyo., wrote in The Washington Post in 2006.

“Another is that administrations of both stripes are loath to disrupt economic activities — i.e., labor supply in factories, farms and businesses,” they added. “And we know that disruptions in the labor supply are the natural, unavoidable and even desirable consequence of strong border and workplace enforcement.”

Reagan and Congress made other miscalculations in writing the 1986 act, including by making it too inflexible to meet the changing needs of the labor market. As a result of its various unanticipated consequences, the number of people estimated to be living in the United States now is, by various estimates, two or three times as large as it was when the law was passed.

But Reagan’s basic idea is sound. The flow of illegal immigration should be considered at both ends: the desperation that drives people to leave their own countries, and the underground economy that exploits them in this one. Even better, consider ways to both accept more immigrants legally and maximize their contributions to society once they get here. Instead of building a wall, let’s consider whether a better kind of bridge makes sense.

Karen Tumulty | The Washington Post

Karen Tumulty is a Washington Post columnist covering national politics. She joined The Post in 2010 from Time magazine and has also worked at the Los Angeles Times.