‘Good Morning America’ news anchor Amy Robach is moving to ’20/20′

Amy Robach is moving off ABC’s “Good Morning America” to take over as co-anchor of the prime-time newsmagazine “20/20.”

ABC News President James Goldston announced Monday that Robach will replace Elizabeth Vargas, who announced late last year that she would leave “20/20” this spring.

Vargas, whose…