In a renewed effort to get Democrats to approve money for his border wall, President Donald Trump claimed that the border wall would quickly pay itself using a simple concept.

Trump had originally promised that Mexico would pay for the wall, but he now says the United States can bear the costs using savings that would come from preventing illegal immigration.

"Could somebody please explain to the Democrats (we need their votes) that our Country losses 250 Billion Dollars a year on illegal immigration, not including the terrible drug flow. Top Border Security, including a Wall, is $25 Billion. Pays for itself in two months. Get it done!" Trump tweeted Dec. 4.

Could somebody please explain to the Democrats (we need their votes) that our Country losses 250 Billion Dollars a year on illegal immigration, not including the terrible drug flow. Top Border Security, including a Wall, is $25 Billion. Pays for itself in two months. Get it done! — Donald J. Trump (@realDonaldTrump) December 4, 2018

The White House did not respond to PolitiFact queries for data backing Trump’s claim.

It’s difficult to pin a hard number on the cost of illegal immigration, because there’s limited data on the population living in the United States illegally. But several immigration experts told PolitiFact they were unaware of any study pegging immigration losses or costs at $250 billion a year. The largest estimate we could find is not even half of Trump’s assertion.

It’s entirely unclear where Trump’s estimate comes from

Trump has previously touched on the country’s fiscal burden from illegal immigration. During the 2016 presidential campaign, he claimed that "illegal immigration costs our country more than $113 billion a year." That was Mostly False.

His latest claim more than doubles the figures he claimed two years ago; most estimates of the unauthorized population remain around 11 million.

The right-leaning Federation for American Immigration Reform (FAIR) estimated in a September 2017 report that the federal, state and local costs of more than 12.5 million people in the United States illegally was around $135 billion a year. After factoring in this population’s tax contributions, the group said the total economic impact of illegal immigration was around $116 billion a year (up from $113 billion in 2013).

The federation seeks to reduce legal and illegal immigration to the United States, and its cost estimates tend to be higher than other related studies. Its conclusions have generally been criticized for relying on inexact estimates and broad assumptions.

Alex Nowrasteh, an immigration policy analyst at the libertarian Cato Institute, said FAIR’s 2017 report was "fatally flawed." It undercounted immigrants’ tax revenues, inflated the number of immigrants in the country illegally, counted millions of U.S. citizens as illegally in the United States, and used a method of estimating fiscal costs "that is rejected by all economists who work on this subject," he said.

Without precise data on the unauthorized immigrant population, researchers typically draw inferences about characteristics based on responses to surveys that don’t ask about authorization status.

Why illegal immigration savings wouldn’t cover wall’s cost "in two months"

Trump claimed that a $25 billion border wall would pay itself in two months, under a scenario where illegal immigration costs $250 billion a year.

There are obvious problems with the numbers. And overall, the total cost of a complete border wall is unclear. But the real problem is the comparison of one-time construction costs of a border wall to annual costs of net government benefits paid in excess of taxes received.

"Building a wall doesn’t magically remove unauthorized immigrants already in the country," said Ryan D. Edwards, a research associate at the Berkeley Population Center and a curriculum coordinator in UC Berkeley's Division of Data Sciences, in an email. "Only deportations do."

Trump's claim also overlooks the complexities of congressional appropriations and the reasons why many Democrats are hesitant to fund the wall. Democrats say the wall is too costly. They also say there are other ways to secure the border, including the use of technology surveillance and more border patrol agents.

A February 2017 study from the Center for Immigration Studies, which favors low-immigration levels, analyzed data from the National Academies of Sciences, Engineering, and Medicine. The study considered data related to the likely education level of future immigrants crossing the border illegally and their estimated fiscal impact.

"If a border wall prevented 160,000 to 200,000 illegal crossings (excluding descendants) in the next 10 years, it would be enough to pay for the estimated $12 to $15 billion costs of the wall," the analysis said.

The projected savings are based on an average lifetime fiscal burden of almost $75,000 for someone who crossed illegally, but not their U.S.-born children.

Some caveats noted by the analysis:

• The population of immigrants in the United States illegally includes people who overstay a visa; and a southern border wall would not address this issue.

• A large share of the net fiscal costs of illegal immigration is at the state and local levels, yet building a border wall would be a federal cost.

It’s also worth noting that some of the federal costs included in some estimates for illegal immigration include expenditures tied to education and health care — it’s uncertain whether those specifics funds would be diverted to pay for the border wall.

Our ruling

Trump tweeted, "Our Country losses 250 Billion Dollars a year on illegal immigration, not including the terrible drug flow. Top Border Security, including a Wall, is $25 Billion. Pays for itself in two months."

The White House did not provide data or any other information backing Trump’s assessment. Several economics and immigration experts said they were unaware of any report stating that $250 billion figure. It’s difficult to peg an exact cost of illegal immigration, but even high estimates are significantly lower.

Trump’s claim that a $25 billion border wall would pay for itself in two months isn’t supported by the facts, either.

Trump’s claim is inaccurate. We rate it False.