Montero was designated for assignment by Washington on Wednesday, Mark Zuckerman of MASN Sports reports.
With Matt Wieters (oblique) activated from the 10-day disabled list prior to Wednesday's game, the Nationals decided against keeping three catchers on the active roster and removed Montero from the 40-man. He had appeared in four games this season but failed to collect a hit in 11 at-bats. Montero will now be subjected to waivers.