Blunt announced Martin's resignation and the appointment of Department of Revenue Director Trish Vincent as his new chief of staff.
"Ed and I obviously talked about the future of the office and who is the right person to lead the office in a specific set of circumstances and right now that's Trish Vincent and that's my decision and Trish Vincent's the chief of staff," Blunt said.
Blunt avoided answering question about when and how Martin's resignation was envisioned and if the resignation was forced.
"We're not going to give a time line of what happened, when, and that sort of thing," Blunt said. "If you're confused then that's my intent, so, I think we've discussed it, we discussed his desire to move on."
Blunt acknowledged he and Martin spoke about who was the best person to lead the governor's office.
The resignation comes after controversy about how the governor's office handles e-mails but Blunt said he, not his chief of staff, is responsible for his office.
"I'm the governor and I'm responsible for what happens in state government," Blunt said.
Martin has served as chief of staff in the governor's office for the last 15 months and has been outspoken about several issues, most recently the e-mail controversy, the Missouri nonpartisan court clan and the firing of two state employees but the governor said Martin brought diverse groups of people together.
"I think in many ways he was able to bring diverse groups of people together to help us achieve important things and fundamental change does rattle cages I suppose but we're going to continue to push forward with this kind of fundamental change and reform we've delivered over the past nearly three years," Blunt said.
Martin's resignation went in to effect at noon Tuesday but Blunt said he will remain on staff until Jan. 4. Blunt said Martin wants to pursue other opportunities and spend more time with his family.
Vincent will begin her new duties immediately.
Martin was not immediately available for comment.
Prior to her three years as Department of Revenue Director, Vincent was deputy Secretary of State while the governor was Secretary of State.
"I believe she's the right person to lead the office at this time and the right person to help me lead the state of Missouri," Blunt said.