In the ongoing political debate over building a wall on the border with Mexico, President Trump and his allies have what they consider an ace in the hole: At one point, prominent Democrats who currently oppose additional wall funding supported the same thing.

In his Oval Office address on Tuesday, Trump called out Senate Minority Leader Charles E. Schumer (D-N.Y.) specifically.

“Senator Chuck Schumer, who you will be hearing from later tonight,” Trump said, “has repeatedly supported a physical barrier in the past, along with many other Democrats. They changed their mind only after I was elected president.”

In another tweet, Trump quoted his predecessor (while misspelling his name) and the woman he defeated in the 2016 presidential election.

All of this is true. All of these quotes are accurate. There’s just one catch: Those requests for additional barriers on the border with Mexico preceded the passage of the Secure Fence Act of 2006, signed into law that October by George W. Bush and supported in the Senate by Schumer, Obama and Clinton.

The result of that law was precisely what Trump now advocates: many more miles of pedestrian and vehicle barriers on the border. The Center for Investigative Reporting’s Reveal mapped the existing wall, indicating what type of barrier it is and when it was built relative to the passage of the Secure Fence Act.

All of that red was added after that law was enacted. Put another way, when Schumer, Obama and Clinton supported additional barriers, the only barriers on the border were the ones indicated in black.

It’s true that much of the additional barriers were meant to prevent the entry of vehicles, not people. As of September 2017, 300 of the 705 miles of barriers on the border with Mexico were designed to prevent the “unbelievable vehicles” used by smugglers from crossing into the United States. Trump has since called for those barriers to be replaced with his much taller wall.

So that’s the context for the prior arguments of the Democrats that Trump opposes. But there are other considerations that would probably disincline Democrats from supporting a new wall, even if those new barriers hadn’t been erected.

For one thing, there are far fewer apprehensions on the border now than there were 13 or 20 years ago. (Apprehensions tally the number of arrests made by Border Patrol agents between established border checkpoints.) Part of that is probably attributable to the new fencing, but much of it stems from the economic slowdown that accompanied the recession. Since the recession, those figures haven’t recovered.

As we’ve noted before, most of those who joined the ranks of the undocumented in the United States in recent years have overstayed visas that brought them to the country legally and did not cross the border illicitly.

In other words, there’s less immediate demand for a wall than there might have been 13 years ago.

What’s more, opinions among Democrats have shifted. At the time the Secure Fence Act passed, Democrats and Republicans were about equally likely to say immigration was a “good thing,” according to Gallup polling. About two-thirds of the members of each party held that position.

Since then there’s been a divergence: Republicans are about as likely now to say that immigration is a good thing as they were then, while Democratic support for immigration has climbed dramatically.

So, in summary, yes, Democratic leaders used to support building barriers on the border. Since they did so most vocally, new barriers were built, illegal border crossings declined, and the Democratic base became more welcoming of immigration broadly.

All of which are reasons that Democrats now decline to indulge Trump’s effort to deliver on his campaign promise.