The team then placed King on waivers. If he is not picked up by a Major League club by Tuesday, he can go back to Columbus. But King is expected to elect free agency instead. Neither King nor general manager Jim Bowden were available for comment.
On Thursday, the Nationals optioned King to Columbus and selected the contract of left-hander Mike O'Connor from the same Minor League team.
The Nationals needed a reliever who can pitch a lot of innings because the bullpen was taxed, and they couldn't use Chad Cordero because of shoulder problems at the time. King is considered a lefty specialist who can get only lefties out, and it was rare when he pitched a full inning.
O'Connor was expected to be the long man out of the bullpen, but he became a lefty specialist on Friday and walked Matt Murton with the bases loaded. O'Connor was taken out of the game after that.
"With our bullpen right now, we can't afford to have a lefty specialist like Ray to pitch to one or two guys," manager Manny Acta said on Thursday. "We need a guy who can give us more than one inning, could pitch to lefties and righties and bridge the gap -- like O'Connor."
King, 34, last pitched on Tuesday against the Mets, giving up two runs in two-thirds of an inning. He pitched in 12 games and gave up four runs in 6 1/3 innings.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.