As the hours count down to a dramatic shift in US immigration policy and an expected surge of migrants at the southern border, those already waiting to enter from Mexico are increasingly desperate.

Beneath an unrelenting sun, hundreds of people are standing in a dry and dusty wasteland. Waiting.

Hungry and thirsty, exhausted and frightened, they have all gathered right beside the huge steel border fence that separates them from the United States. They can see through it, to the place they have sacrificed so much to try to reach.

But no-one knows if they will be allowed across that border.

Rosario Medina says that to find food for her grandchildren she has been sifting through dumpsters, and even gathering water for the babies bottles from the polluted Rio Grande river.

No wonder tears roll down her face as she describes trying to survive here for the past eight days, as the children’s lips blister in the sun.

To meet these people, I first had to step across that stinking river and then crawl in the dirt through a small gap in the razor wire fence. I then heard the stories of the frightening journeys many of these people had endured.

MiLexi Gomez told me about travelling from Venezuela, taking her four young children through unmarked jungle, carrying them up mountains and then having to jump on top of trains when they could not afford to buy tickets. Now they are all having to sleep in the dirt, she fears the colds her twin boys are suffering could turn to bronchitis.

“We are feeling desperate” she says. “We can’t sleep at night because it’s too cold. We don’t have money to eat, we have no way to wash. I ask God what I should do to protect my children in this place”.