Several thousand migrants are leaving southern Mexico with goals of reaching the U.S., as President Joe Biden hosts the Summit of the Americas in Los Angeles.

Leaders from the Americas will meet through Friday to discuss immigration, climate change, COVID-19 and other issues.

But the presidents of El Salvador, Honduras, Guatemala, and Mexico won't be attending.

Their countries are some of the leading "migrant-sending and transit countries."

The president of Mexico, Andrés Manuel López Obrador is boycotting the summit, because the U.S. did not invite Cuba, Nicaragua, and Venezuela to the conference.

Their collective absence has caused controversy, raising doubts about the summit.

Migrant caravan activists hope this latest caravan will bring immigration issues to the forefront of the conference anyway.

Biden is expected to propose an economic framework proposal during the summit, according to a White House official, POLITICO reports.

The framework will reportedly address supply chain, immigration, and food security issues.

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