A caravan of at least hundreds of migrants departed from Tapachula, a city in southern Mexico, and headed for the southern border of the United States.

The smaller caravan is presently stalled in the town of Huixtla, around 25 miles (40 km) north, where it intends to join a larger caravan that departed six days ago.

Organizers said the first had swelled to some 7,000 people while the government in the southern Chiapas state said it estimated the group at 3,500 people.

Many migrants are fleeing poverty and political instability in their homelands, hailing from Cuba, El Salvador, Guatemala, Haiti, and especially Honduras and Venezuela, according to a Reuters witness.

“I think 3.4 months is too long to wait to get a humanitarian visa, to be able to travel through Mexican territory,” said Selma Alvarez from Venezuela. “Because we are at the mercy of coyotes, of criminals, it is good that we accompany each other in the caravan, it seems safer to me.”

Alvarez added that the group was impatient to get to the U.S. border and start the process to enter the U.S. with appointments secured via a U.S. government app, CBP One, and request asylum.

U.S. President Joe Biden, who is seeking reelection next year, is under pressure to lower the number of people crossing illegally into the U.S. from Mexico.

A record number of people this year have crossed the Darien Gap region connecting Panama and Colombia.