MEXICO CITY - Migrants, trade, crime, the border wall: The challenges to the modern US-Mexico relationship have perhaps never been as stark and divisive as they are now, at a critical juncture for both countries.

With a new president preparing to take power in Mexico City this weekend and the current US administration set to enter its third year, the two neighbors find themselves lurching between crisis and opportunity. While a trade dispute that US President Donald Trump had fanned with great enthusiasm seems set to ease, the other issues remain unresolved and potential flashpoints for both countries.

"This is really a key moment," said Earl Anthony Wayne, a former US ambassador to Mexico. "There are very serious short-term problems that have to be managed and managed in a way that can solidify relations over the course of the next six years."

President-elect Andres Manuel Lopez Obrador takes office on Saturday, just a day after the two nations and Canada are to sign a replacement accord for the North American Free Trade Agreement, which Trump lambasted during the 2016 campaign and vowed to cancel.

Meanwhile, thousands of Central American migrants are digging in for a long haul at a filthy, overcrowded sports complex in sight of the United States, while a small number have opted to return home after clashes with border forces dimmed hopes of crossing.

The bedraggled men, women and children of a caravan of mostly Hondurans began cramming into the complex in Tijuana about three weeks ago. They now number more than 6,000 in a space the city government originally prepared for a third as many.

But despite the difficulties, many seemed determined to wait in Mexico for their chance to make their case to the US, with more than 600 applying for permits to work in Mexico on Tuesday alone, according to the foreign ministry.

"It cost me a lot to walk almost 15 to 20 hours a day, and to go back now: no," said Anabell Pineda, 26, who has pitched a tent in the stadium beside a neat pile of bags and rolled-up blankets.

Pineda, who had traveled for almost a month from the violent northern Honduran city of San Pedro Sula with her 6-year-old son, said she had arrived in Tijuana 13 days earlier, feeling unwell.

When she learned it would be nearly impossible to cross the border quickly under current US policies, she resolved to be patient, and get a Mexican work permit meanwhile.

Mexican Foreign Minister Luis Videgaray, who leaves office this weekend, said in response that Central American migrants were welcome to stay in Mexico.

But he said the migrants have a right to request US asylum, and Mexico has repeatedly refused US requests to force them to seek refuge there instead.

Ap - Reuters