Voth was optioned to Triple-A Syracuse on Monday, Chelsea Janes of The Washington Post reports.
Voth will head back to the minors after spending just one day with the Nationals and making no appearances. He'll rejoin the starting rotation at Triple-A Syracuse, where he owns an impressive 0.96 ERA, 0.70 WHIP and 22:2 K:BB through four starts (18.2 innings) this season.