Thousands of Central Americans migrants making their slow trek through Mexico have reportedly stopped to rest Thursday in the small city of Juchitan de Zaragoza, with plans to walk towards Matias Romero, a city in southwest Mexico.

The caravan, which began on Oct. 12, was initially estimated at about 5,000 to 7,000, but that number has reportedly dipped significantly due to fatigue and illness. The Associated Press on Sunday estimated that the number was 4,000 migrants.

On Thursday, another group of migrants, estimated at about 1,000, reached the Mexican city of Huixtla, which is located near the Mexico-Guatemala border. Huixtla is about 200 miles south of the first caravan.

Coordinators for the migrants have not disclosed their northbound route.

Juchitan de Zaragoza is located about 895 miles south of the border town of McAllen, Texas. Based on their current pace, it could take months for the caravan to reach the U.S.-Mexico border.

According to the Associated Press, the migrants failed to gain bus access from Juchitan de Zaragoza, forcing them to travel by foot or use other means of transportation.

President Donald Trump, who said he could deploy as many as 15,000 troops to the border, has turned the migrant caravan into a hot-button campaign issue ahead of Tuesday's midterm elections.

Critics have decried the move as a political stunt. A political ad tweeted by Trump included footage of the migrant caravan.

The Pentagon on Tuesday said it will send over 5,200 troops to the border by the end of the week.

"What I can confirm is there will be [an] additional force over and above the 5,239. The magnitude of that difference? I don’t have an answer for you," U.S. Northern Command and North American Aerospace Defense Command head Gen. Terrence O'Shaughnessy told reporters.