Tuesday's scheduled fourth game of the best-of-five series was postponed by rain. The game, which was to begin at 4:38 p.m. CT, was delayed and then officially postponed 35 minutes later.
The game will has been rescheduled for 3:08 p.m. CT (4:08 ET) on Wednesday. Chicago leads the series 2-1.
"Both clubs were pretty much on the same page (about the postponement) because the first thing (is) ... you really don't want to burn your pitchers at this point," Chief Baseball Officer Joe Torre told TBS.
Cubs manager Joe Maddon said Tuesday afternoon that Jake Arrieta would start for the Cubs if the game was postponed. Nationals manager Dusty Baker said he would make a determination who will pitch for the Nationals.