Group uses caravans to shine light on the plight of migrants — but has that backfired?

TIJUANA, Mexico - As a cold rain fell in Tijuana, a group of Central Americans faced off with Mexican police sent to block them from launching a hunger strike near the U.S. border.

Leading the migrants were activists from the group Pueblo Sin Fronteras, or People Without Borders.

The small collective of volunteers based in the U.S. and Mexico helped create the migrant caravan trend; it organized the first caravan to the U.S. border last year and has helped guide the groups now in Tijuana.

It says the caravans help protect migrants from rape, kidnapping and other perils while drawing attention to the reasons they flee and their treatment on the journey north.

But Pueblo Sin Fronteras has drawn considerable criticism. Conservatives accuse the group of human trafficking. And some former allies on the left say it is using migrants to advance its political agenda -