Yost made the announcement in an e-mail to staff on Wednesday.

Collipriest has been Bennett's press secretary and communications director since he was elected. Before that she worked as press secretary for Sen. Jake Garn.

“MJ has an outstanding knowledge of the Senate, politics, campaigns, DC and Utah politics,” Yost wrote in the announcement. “She will do an outstanding job as the chief of staff.”

Mark Morrison will become Bennett's deputy chief of staff and continue to serve as the senator's legislative director.

Yost, the son of retired Adm. Paul Yost, former commandant of the Coast Guard, is leaving at the end of August for the private sector, although he has not decided what he will do.

- Robert Gehrke