Should the Dolphins fulfill the Rooney Rule, which requires teams to interview at least one minority candidate for an open head-coaching job, Harbaugh's hiring in Miami could happen quickly.
The Dolphins' interest in Harbaugh increased after they failed to land former Tampa Bay Buccaneers and Oakland Raiders coach Jon Gruden. Dolphins owner Steve Ross, general manager Jeff Ireland and team consultant Carl Peterson, a former NFL executive, flew to California late Wednesday to meet with Harbaugh on Thursday.
There remains the possibility that attempting to pry Harbaugh away from Stanford will prove to be a fruitless exercise. The coach remains a very real candidate to stay at the school, according to a source.
One source close to the decision estimated that ultimately it could come down to the two Bay Area entities -- Stanford and the 49ers.
Harbaugh is seeking a deal worth around $6.5 million per season, which Pete Carroll received from the Seattle Seahawks last year to leave USC. And while several people close to Harbaugh have advised him against going to the 49ers because of their front-office structure, he has received more favorable reports on Ireland and the Dolphins.
Ross, Ireland and Dolphins CEO Mike Dee were on the Stanford sideline before Monday's Orange Bowl in Miami, and league sources said the team has made repeated contact with Harbaugh after finishing 7-9 for the second consecutive season.
The Dolphins have been unwilling to blow up their football-operations department, which took them out of the running for former Pittsburgh Steelers coach Bill Cowher. Dolphins officials believe they need to make a splash and land a coach who can have the team play more attractive football than Tony Sparano -- who's still employed at the moment -- and make Miami more riveting in what can be a fickle professional sports market.
Sparano and his staff are hanging in the balance, and league sources told NFL Network insider Albert Breer that Dolphins coaches are "preparing for the worst," but no announcement has been made about their future with the team.
The Miami Heraldreported Thursday night that offensive coordinator Dan Henning is the first member of the staff to exit the picture. Henning agreed with Sparano that it would be best to part ways, according to a source close to the coordinator.
It's unclear whether Henning will look for new employment or retire. He served as offensive coordinator in Miami for three seasons.
Working in the 49ers' favor, several sources say, is that Harbaugh already lives in the Bay Area with his young family. Over the past week, Harbaugh has focused more on NFL opportunities, with the University of Michigan, where he played, losing traction as a possibility.
Michigan athletic director Dave Brandon has said he expects Harbaugh to take an NFL job.
Ross also is a Michigan graduate and a major contributor to the university, where the school of business carries his name.
With so many suitors, Harbaugh is in a position to call the shots, though he has a tendency to go back and forth at times. Harbaugh doesn't want to string along his players, coaches and officials at Stanford any longer than need be, which also could result in a resolution by the weekend.
The 49ers announced Trent Baalke as their new general manager Tuesday night, and he has said he expects to have a coach in place by Friday, a team source said. Coach Mike Singletary was fired after a 25-17 loss at St. Louis on Dec. 26 that eliminated San Francisco from the playoffs for an eighth consecutive season.
The 49ers interviewed Oakland Raiders offensive coordinator Hue Jackson on Wednesday, but New York Giants defensive coordinator Perry Fewell will "slow play" San Francisco, according to a source, because he is very sensitive to being used to accommodate the Rooney Rule. It's clear to Fewell that Harbaugh is the 49ers' top choice.
NFL Network and Fox analyst Brian Billick remains a candidate for the 49ers job, assuming Harbaugh doesn't take it.
The 49ers, through the process of interviewing general managers, heard sterling recommendations for former Denver Broncos coach Josh McDaniels and consider him a strong head-coaching candidate. However, a source close to McDaniels said it's highly unlikely he would go to San Francisco because of issues with the personnel and front-office structure.
Had the 49ers changed their structure and been willing to hire an outside GM, and meet the financial threshold that Harbaugh is commanding on the market, they could have built a dream staff, according to sources.
NFL Network insider Michael Lombardi interviewed for the GM position Tuesday in San Francisco. Lombardi has strong ties to Harbaugh, but also McDaniels, with the possibility of having McDaniels as offensive coordinator and another former head coach as defensive coordinator.
Harbaugh, 47, has been at Stanford since 2007. This season, he led the Cardinal to a program-best 12-1 record and an Orange Bowl victory over Virginia Tech.
Harbaugh is 58-27 overall as a college coach and 29-21 in four seasons at Stanford. He took over a 1-11 Cardinal team when he was hired in December 2006 and quickly turned the program into a winner and bowl contender.
Many believe Harbaugh, who played 15 seasons in the NFL, is ready to make the leap to the next level and is eager for a new challenge. He was the Oakland Raiders' quarterbacks coach from 2002 to 2003 before spending three seasons as head coach at the University of San Diego.
Harbaugh's brother, John, is the coach of the Baltimore Ravens, who are in the playoffs as a wild-card team this season.
The Associated Press contributed to this report.