Before their opener against Arizona, the Reds completed their roster with several other anticipated moves. They put right-hander Matt Belisle, catcher David Ross and shortstop Alex Gonzalez on the 15-day disabled list.
The Reds also designated left-handed reliever Jon Coutlangus for assignment to the minors.
The 40-year-old Stanton had a 4.50 ERA in six spring training appearances, falling behind Jeremy Affeldt and Kent Mercker in the competition for left-handed relief roles. The Reds indicated last week that they were planning to get rid of Stanton, who can accept or reject the demotion.
If he rejects the move, the Reds would have 10 days to trade or release him. If he pitches in the minors or gets released, the Reds will still have to pay his $3 million salary for this season, plus a $500,000 buyout on his 2009 option.
General manager Wayne Krivsky thought he was filling the Reds' need for a late-inning, left-handed reliever when he offered Stanton a $5.5 million, two-year contract in November 2006. His offer was much more generous than what Stanton got from any other team.
"He's played a long time," Krivsky said Monday. "That was the deal it took to sign him at the time, and here we are."
He went 1-3 with a 5.93 ERA in 69 appearances last season, when the Reds had the NL's worst bullpen. Cincinnati gave up 123 runs in the eighth inning, the most in the league.
"I like Mike Stanton a lot," Krivsky said. "I only wish him the best. We just felt at this point in time that a couple of people were ahead of him."
Belisle is recovering from stiffness in his right forearm, which started bothering him late in spring training. Ross missed most of spring training with lower back spasms. Gonzalez has a compression fracture in his left knee.