A Broncos spokesman said Thursday there was no interview scheduled.
The Denver Post reported Friday that an NFL source told the paper that the Broncos won't interview Harbaugh and that their interest had cooled. The Post reported that the Broncos talked about having Harbaugh interview in Denver earlier in the week and discussed traveling to the San Francisco area to interview him later in the week, but neither meeting could be arranged.
Mortensen reported late Thursday that Dolphins coach Tony Sparano, who has a year left on his contract, would be retained.
Harbaugh met Thursday with Dolphins owner Stephen Ross in the San Francisco area about the Dolphins' job, sources told Mortensen. But after the meeting, Harbaugh was still considering staying at Stanford, a source told The Associated Press.
Ross resumed the meeting Thursday night with Harbaugh's agent, David Dunn, in Southern California after the Dolphins owner traveled south to satisfy an unrelated business commitment following his meeting with Harbaugh, the sources said.
Harbaugh also met Thursday with the president of Stanford and the university provost. The school made an amended offer to the coach with enhancements from an offer presented in early December.
Harbaugh had met with the 49ers for five hours on Wednesday, a source told Mortensen. The 49ers are willing to up their offer to more than $6 million a season to make Harbaugh their next head coach, a source said.
Harbaugh returned Tuesday night to the Bay Area from a 40-12 Orange Bowl victory over Virginia Tech in Miami that gave the Cardinal a program-best 12-1 record.
The Broncos are interviewing New York Giants defensive coordinator Perry Fewell and interim Denver coach Eric Studesville on Sunday.
Earlier Thursday, Atlanta Falcons offensive coordinator Mike Mularkey canceled an interview with the Broncos scheduled for Friday, saying he doesn't want to take too much time away from his preparation for next week's playoff game.
John Elway, the Broncos' new executive vice president of football operations, is spearheading the search. The Broncos are looking to replace Josh McDaniels, who was fired Dec. 6.
Elway said he wanted to hire a coach who already had head coaching experience, preferably in the NFL, and both Fewell, 48, and Studesville, 43, have been interim head coaches, Fewell for seven games in Buffalo in 2009.
"I don't believe anybody that's not had that NFL experience can make that jump -- other than Harbaugh. There's nobody [else] in the college ranks that we're interested in talking to," Elway said. "And preferably we'd like to have some head coaching background in the NFL, but it's not a must. If there's a guy who's a coordinator that's up and coming and shows that he can be the head coach and understands that, then he'll be the guy."
The Dolphins were willing to make Harbaugh the highest-paid coach in the NFL, which would place his salary in the $7 million-to-$8 million range, sources said.
"Stanford is still a viable option" for Harbaugh, the source said. He could return to coach quarterback Andrew Luck and what is said to be a strong recruiting class, and see what NFL options exist next year.
Luck, the odds-on favorite to be the No. 1 pick in this spring's NFL draft, announced Thursday he will stay in school and play his redshirt junior season.
Harbaugh is 58-27 overall as a college coach and 29-21 in four seasons at Stanford. He took over a 1-11 team when he was hired in December 2006 and quickly transformed the program.
Harbaugh played 15 seasons in the NFL for the Bears, Colts, Ravens, Chargers and Panthers. He also has NFL coaching experience -- he was the Raiders' quarterbacks coach in 2002-03, then spent 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 AFC playoffs.
The Associated Press contributed to this report.