Astros general manager Ed Wade made the announcement after Houston's 5-4 win over the Detroit Tigers on Friday night. Wade said that because Backe is a player with five or more years of Major League service, he has the right to accept an outright assignment to the Minors or reject it and demand his release.
"We'll deal with whatever decision he makes," Wade said. "Because of the injury he had during Spring Training, it just put him in a position where other guys have moved ahead of him. We've offered him the opportunity to stay in the organization, but certainly it's his call whether he wants to do that or pursue something outside of the organization."
If Backe rejects outright assignment, Houston has 10 days to dispose of his contract, other options which include trading him or releasing him.
Backe made his first and only start of the season against the Rangers last week, taking the rotation spot of Mike Hampton, who was placed on the disabled list with a strained left groin. He gave up four hits and three runs in four innings in Arlington, and he was forced to leave the game with a finger blister.
In five appearances this season, mostly out of the bullpen, Backe has accumulated a 10.38 ERA.
"He's been a model citizen and a big part of our ballclub," Wade said. "I felt rather than this just being a roster move announcement, I should come in and say a little more. He put his best foot forward every opportunity he had for us."
The news came as a shock to the eight-year veteran.
"I don't know what I want to do," Backe said. "I have to talk to my agent and to be honest, hopefully, some other team picks me up, and I can get to the big leagues. We'll have to take it one step at a time.
"I've never been in this situation before. I just hope someone is out there that knows the person that I am and the competitor that I am. I'm still hungry. I know I haven't done well here, but a lot of situations I've been in on the field with the Astros has been something out of the ordinary for me. Hopefully, I can find someone who needs a starter and I can get back in a starting role."
Backe struggled last year, going 9-14 with a 6.05 ERA in 31 starts in his first full season since undergoing Tommy John elbow ligament replacement surgery. He signed a $1.55 million contract and went into Spring Training competing for a spot in the Astros' rotation, but an injury to his rib-cage muscle in early March put him on the shelf.
When Backe returned from the disabled list, he was put into the bullpen. As a reliever, he allowed 12 runs on 17 hits, striking out 10 over four appearances.
"I was thrown into something that was out of the norm and was expected to do well," Backe said of his designation to the bullpen. "It was tough to just battle the mental demons inside with being treated the way that I was."
Jason Grodsky is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.