Standing on the banks of the Rio Grande, Guillermo Caldera knows he is in the “fight of his life”. For 20 years, he has built his business fixing up damaged cars off the streets of Laredo, Texas, to ship across the border to his countrymen in Mexico, at prices they can afford.

“I’ve built my business here from the ground up,” says the 46-year-old. “Now they want to take that ground away.”

Guillermo’s workshop stands within feet of the river that acts as the border between the US and his native Mexico.

He is one of dozens of landowners who Donald Trump wants “bullied” into handing over their properties to make way for his “big, beautiful wall”.

But the determined dad-of-six, who is now a US citizen, is fighting back – taking his own government and Trump to court to stop their plans.

And he is far from alone.

In 2016, Trump’s signature policy to win the White House was the promise of a 30ft border wall.

At rallies he encouraged chants of “Build the wall. Build the wall” from supporters, while telling them they would not pay a dime towards it and that Mexico would foot the bill.

Fours years on – despite his repeated boasts of “promises made, promises kept” – not one peso has been handed to the US for his dream barrier.

So far, only five miles has been built.

Yet taxpayers have now shelled out more than £9billion and counting, as the President was forced to raid money from the military when Congress denied him the funds.

Repeated setbacks have not deterred Trump’s assault on immigration.

One of his most damning policies is separating migrant children from their parents as they crossed the border.

In last week’s final Presidential debate with White House rival Joe Biden, Trump’s lack of humanity shone through when discussing the 545 children torn from their parents’ arms.

Asked about the issue by moderator Kristen Welker, he boasted: “They’re so well taken care of. They are in facilities that are so clean.”

Biden called the actions of Trump’s administration “criminal”.

The former Vice President said: “It violates every notion of who we are as a nation.

“Those kids are alone with nowhere to go.”

Trump, who insisted during the debate he was “the least racist person in the room”, then attacked the policy by local enforcement to let those they catch walk free until their case is heard, rather than locking them up.

Falsely claiming most never showed up at court, he said: “They never come back. Only the really… I hate to say this, but those with the lowest IQ… they might come back.”

The comment drew an immediate backlash on Twitter. Trump has questioned the IQs of others in the past, many of whom were people of colour.

In reality, 99% of asylum seekers have appeared for their hearings over the last year, according to an immigration think tank at Syracuse University.

Trump’s lies are something people in Laredo know only too well. Outside its courthouse is a bright yellow Defund The Wall mural in 30ft letters. Nowhere along the 2,000-mile border is there greater opposition to his plans.

Less than 50 yards away across the Rio Grande is the Mexican city of Nuevo Laredo. The cities share a 123-year-old tradition, holding the nation’s largest celebration of George Washington’s birthday.

They come together in an abrazo – a hug – on the bridge that separates them, for a month-long display of both patriotism and binational unity.

The sister cities feel a sense of the unbreakable bond between them. They call it “los dos Laredos”, a symbol of one community sharing two sides.

But the clock is ticking in this crucible of national friendship.

If Trump wins next week’s election, the wall, he brags, is coming.

The only thing people here want is a Biden win, to save them being caged in by 32 miles of steel and concrete.

All along the Texas border, there is outrage. Who is Trump, people ask, to seize their private property on land they have occupied for generations?

But in Laredo the anger is especially strong. A city of 260,000, Laredo lives off international trade – and prides itself on its 265-year history.

To defend that heritage, local officials have worked to slow down the Trump administration.

In January, the city council denied US Customs and Border Protection (CBP) permission to survey about 1,000 acres of property along the river. Federal attorneys then sued for access.

To justify their plans, Trump and his administration characterise Laredo as a crime-riddled city, at the mercy of cartels who send over killers, rapists and child-smugglers in their droves.

The CBP, which oversees border security, says the new wall is needed because “the Laredo sector is an area of high illegal activity”.

They talk of having stopped more than 21,750 illegal aliens and 30,150lb of drugs in this financial year.

And they insist: “These projects will improve Laredo sector’s ability to impede and deny illegal border crossings and drug and human smuggling.”

But while Nuevo Laredo, in Mexico, is plagued with violence, the difference across the water is like night and day.

Locals say Trump would have anyone believe border cities such as El Paso, Brownville and Laredo are extremely violent and in need of a wall.

Yet the FBI says Rio Grande Valley, on which they sit, is exceptionally safe.

Of the 24 Texas metro areas ranked by the bureau, Brownsville comes in last, with 240 violent crimes per 100,000 people. El Paso and Laredo place at 13 and 10 respectively – while the murder rate in each is incredibly low.

Campaigner Elsa Hull, a riverside landowner, says: “It’s not a war zone. Nor do we have an invasion.

“Trump is trying to militarise the border. It’s all hyped up to the people that don’t live here and they’re buying into all these lies.

“I live with my two teenage daughters. A bunch of women right next to the river – we don’t fear for our safety.

“Sure there are problem areas where people cross, but if border patrol wants to secure the borders, concentrate on the areas that are the problem. A wall is just going to divide people, which is exactly what Trump wants.

“The majority of the problem, the drugs, that’s a billion-dollar industry.

“You seriously think people are crossing billions of dollars of drugs in a backpack swimming across the river? That’s ridiculous.”

The federal agency has given contracts for the project to an Alabama firm and to the builder of a controversial private border wall.

But most of the land is still in private hands. Elsa, 52, adds: “They want to put up this freaking 30ft monstrosity, and the enforcement zone is as wide as a four-lane highway – the town will be wiped out.

“They’re awarding these construction contracts but they don’t have the land yet. That’s their tactics. They’re trying to bully people, to scare people.”

It was announced last year that the entire city would be walled off, galvanising the grassroots coalition.

Asked about the election, mum-of-two Elsa said: “All will be lost if Trump gets another four years.

“This administration is the worst thing that’s ever happened to our country. It’s just going downhill.

“Every inch of progress we might’ve made on environmental issues, human rights issues… they’re being trashed.

“He’s a liar. He’s a racist. He’s a fascist dictator. He is evil. He has to go. He is not welcome here.”

The new border wall contract is valued at about £13million per mile.

That contrasts with the £75 offered to people such as Guillermo to access their land for a year – or the “paltry” sum on the table to take it from them.

But for the businessman, it would not matter if they offered him £75,000 – his land is not for sale at any cost.

He said: “We should build bridges, not barriers. I was born and raised in Nuevo Laredo, my family still live there. Do I want to see them through a cage? Isn’t that what Trump puts kids in?”