Bush took over for Jim Hendry, who was dismissed on Friday as the GM. Cubs chairman Tom Ricketts said he wanted to hire the next GM from outside the organization, and he met Wednesday with Bush to give him the news.
"[Ricketts] told me he felt we needed a fresh start and he was going to look outside the organization," Bush said. "I really appreciated his honesty, to be honest."
Bush said he told Ricketts he "would get my very best effort."
"I feel a tremendous obligation to make good decisions here in the interim and to do our very best to transition to new leadership in as efficient a manner as we can," Bush said.
If the Cubs are approached regarding a waiver trade before end of the season, Bush will handle it, and he will communicate with Ricketts.
Bush got started right away with a staff meeting Friday. He was promoted to assistant GM on Dec. 20, 2006, after serving as a special assistant to the GM. He spent his entire 12-year Major League playing career with the Twins, playing on two World Series championship teams, in 1987 and '91.
Even though he won't be considered for the general manager's job, Bush said he would like to stay with the Cubs in some capacity.
"I'm very realistic, and I understand that the new GM will come in and evaluate who fits where and how it all fits going forward," Bush said. "This has been a great opportunity for me and I've learned a lot, and I would be thrilled and honored if there was some way I could [stay] going forward."
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter@CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.