Rainey was recalled by the Nationals to serve as the 27th man for the second game of Wednesday's doubleheader against the Mets, Jessica Camerato of MLB.com reports.
Rainey will provide a fresh arm out of the bullpen in Wednesday's nightcap after the Nationals and Mets concluded a suspended game in the afternoon. The right-hander has been in the minors since the beginning of August, but he's posted a 7.20 ERA and 1.76 WHIP in 25 innings across 31 relief appearances in the big leagues this year.