Harbaugh was the second-longest serving coach in the NFL behind long-term divisional rival Mike Tomlin, who chose to end his 19-year spell with the Pittsburgh Steelers after they lost in the first round of the play-offs.
The Steelers are now looking for just their fourth head coach since 1969 and are reportedly scheduled to speak to former Green Bay Packers and Dallas Cowboys coach Mike McCarthy, plus former Miami head coach and current Minnesota Vikings defensive co-ordinator Brian Flores.
They are also one of several teams who have interviewed or are hoping to interview Packers defensive co-ordinator Jeff Hafley, Los Angeles Chargers defensive co-ordinator Jesse Minter and Los Angeles Rams defensive co-ordinator Chris Shula.
The Baltimore Ravens have interviewed multiple candidates, including Flores, his Miami successor Mike McDaniel and ex-New York Jets head coach Robert Saleh, who returned to his former role of San Francisco 49ers defensive co-ordinator last year.
The Rams’ pass-game co-ordinator Nate Scheelhaase and Seattle Seahawks offensive co-ordinator Klint Kubiak have been interviewed by multiple teams, including the Ravens.