Singer was optioned to Triple-A Omaha on Thursday, Alec Lewis of The Athletic reports.
Singer began the season in a bullpen role and posted a 6.35 ERA and 1.41 WHIP in 5.2 innings during three relief appearances. He'll attempt to right the ship as a starter in the minors and will presumably be an option to fill in if the Royals' rotation staff deals with injuries at some point, per Lynn Worthy of The Kansas City Star.