Voth was called up to the majors, Mark Zuckerman of MASN Sports reports.
Voth will be available out of the bullpen if necessary, but the Nationals hope to have him start Saturday against the Mets. The 26-year-old has yet to make his major-league debut. He has a 3.55 ERA in 15 starts for Triple-A Syracuse this season. Jefry Rodriguez was optioned in a corresponding move.