HUIXTLA, Mexico — Little by little, sickness, fear and police harassment are whittling down the migrant caravan making its way to the U.S. border, with many of the 4,000 to 5,000 migrants camped overnight under plastic sheeting in a town in southern Mexico complaining of exhaustion.

The group, many with children and even pushing toddlers in strollers, planned to depart Mapastepec at dawn Thursday with more than 1,000 miles still to go before they reach the U.S. border.

But in recent days a few hundred have accepted government offers to bus them back to their home countries.

Jose David Sarmientos Aguilar, a 16-year-old student from San Pedro Sula, Honduras, was one of at least 80 migrants waiting in the town square of Huixtla, where the rest of the caravan departed Wednesday morning, for four buses that would take them back to Honduras.

Sarmientos Aguilar said it was partly the spontaneous nature of the caravan — many people joined on the spur of the moment — as well as the rumours of migrants dying that did him in.

He joined the march “without thinking about what could happen and the consequences it could bring,” he said. He said the death of a migrant who fell off a truck Monday — and vague rumours of two migrants killed in Huixtla — also pushed him to return.

“There have been a lot of tragedies. It’s not necessary to go on losing more lives to reach there (the U.S.),” he said. “I am a little sick in the chest. I have a cough. And so instead of risking getter sicker and something happening to me, it’s better to go home.”

Carlos Roberto Hernandez, of Yoro province in Honduras, has a rumbling cough. For him, it was the scorching heat during the day and the evening rains that led him to drop out.

“We got hit by rain, and ever since then I’ve had a cold,” Hernandez said. Asked if he would make another attempt to reach the U.S., he said emphatically: “No. I’m going to make my life in Honduras.”

For Pedro Arturo Torres, it appeared to be homesickness that broke his determination to reach the U.S.

“We didn’t know what lay ahead,” said Torres. “We want to return to our country, where you can get by — even if just with beans, but you can survive, there with our families, at peace.”

The Mexican federal government’s attitude has also played a role in wearing down the caravan.

All the food, old clothes, water and medicine given to the migrants have come from private citizens, church groups or sympathetic local officials.

The federal government hasn’t given the migrants on the road a single meal, a bathroom or a bottle of water. It has reserved those basic considerations only for migrants who turn themselves in at immigration offices to apply for visas or be deported. Officials say nearly 1,700 migrants have already dropped out and applied for asylum in Mexico.

Sometimes federal police have interfered with the caravan.

In at least one instance, The Associated Press saw federal police officers force a half-dozen passenger vans to pull over and make the drivers kick migrants off, while leaving Mexican passengers aboard. In a climate where heat makes walking nearly impossible at midday, such tactics may eventually take a toll on migrants’ health.

In Mapastepec, where the main group stayed Wednesday night, it appeared the size of the caravan had diminished slightly. The United Nations estimated earlier in the week that about 7,000 people were in the group. The Mexican government gave its own figure Wednesday of “approximately 3,630.”

Parents say they keep going for their children’s futures, and fears of what could happen to them back home in gang-dominated Honduras, which was the main motivation for deciding to leave in the first place.

“They can’t be alone. … There’s always danger,” said Ludin Giron, a Honduran street vendor making the difficult journey with her three young children. “When (gang members) see a pretty girl, they want her for themselves. If they see a boy, they want to get him into drugs.”

Refusing either demand can be deadly. Honduras has a homicide rate of about 43 per 100,000 inhabitants, one of the highest in the world for any country not in open war.

On Wednesday, Giron crammed with her children, 3-year-olds Justin and Nicole and 5-year-old Astrid, into the seat of a motorcycle taxi meant for only two passengers. Also perched on the perilously overcrowded motorbike were Reyna Esperanza Espinosa and her 11-year-old daughter, Elsa Araceli.

Espinosa, a tortilla maker from Cortes, Honduras, said there was no work back home. “That’s why we decided to come here, to give a better future for our children,” she said.

Such caravans have taken place regularly, if on a smaller scale, over the years, but U.S. President Donald Trump has seized on the phenomenon this year and made it a rallying call for his Republican base ahead of the Nov. 6 midterm elections.

Trump has blamed Democrats for what he says are weak immigration laws, and he claimed that MS-13 gang members and unknown “Middle Easterners” were hiding among the migrants. He later acknowledged there was “no proof” of the claim Middle Easterners were in the crowd. But he tweeted Wednesday that the U.S. “will never accept people coming into our Country illegally!”

Associated Press journalists travelling with the caravan have met throngs of Hondurans, as well as Guatemalans, Salvadorans and Nicaraguans, but no one from the Mideast. Many were young people travelling with their families. Again and again, they cited poverty and violence in their countries as reasons for leaving.

Another, smaller caravan earlier this year dwindled greatly as it passed through Mexico, with only about 200 making it to the California border. Those who do make it into the U.S. face a hard time being allowed to stay. U.S. authorities do not consider poverty, which many cite as a reason for migrating, in processing asylum applications.

Carmen Mejia from Copan, Honduras, carried 3-year-old Britany Sofia Alvarado in her arms, and clutched the hand of 7-year-old Miralia Alejandra Alvarado, also sweaty — and feverish.

Mejia said she was worn out. Still, she pledged to go on. “I’ve walked a long way. I don’t want to return. I want a better future for my children.”

Mark Stevenson, The Associated Press