The Wisconsin State Journal was first to report that Wisconsin athletic director Barry Alvarez had offered Andersen the job Tuesday night. Andersen is in his fourth year at Utah State and is coming off his best season yet.
The earliest the new coach could be announced is Thursday, due to the two-week waiting period mandated by the state after a job is posted.
This comes just 19 days after Utah State released a statement saying Andersen was staying in Logan.
"At the end of the day, Logan is where we need to be," Andersen said in the release. "The kids, the administration — we had too much momentum going for me to leave."
That was before the Wisconsin job opened up. Andersen began calling his players and informing them of his decision Tuesday night.
Andersen's son Keegan, a sophomore tight end at Utah State tweeted, "No matter what happens Im still an Aggie. I am going to finish an Aggie! I love all my teammates y'all are my brothers and always will be!"
Senior running back Kerwynn Williams, who rushed for 235 yards and 3 touchdowns in Utah State's 41-15 victory over Toledo in the Famous Idaho Potato Bowl Saturday night tweeted, "All I can say is now is when we as teammates need each other the most. Thankful for what he's done for us and tho we may not all support it."
Junior tight end D.J. Tialavea tweeted, "I love Coach A! But last time I checked, he wasnt the one with the helmet on. "Players make plays, players win games" we gonna be alright."
The 18th-ranked Aggies won the Western Athletic Conference and finished 11-2, the best record in school history.
Utah State lost 16-14 at Wisconsin earlier this season.
Andersen was making around 700 thousand dollars per year at Utah State, but his salary is expected to increase to about 2 million per season at Wisconsin.
The 48-year-old Andersen is 26-24 at Utah State. He took over in Logan, Utah, after spending five seasons as defensive coordinator at the University of Utah under Kyle Whittingham. In the four seasons before Andersen took over at Utah State, the Aggies won a total of nine games.
Bielema left Wisconsin for Arkansas earlier this month in a surprising move.
Andersen's move would come as a surprise only because he has so publicly stated recently that he planned to stay at Utah State after turning down other offers in the past month. The Utah native was a candidate at Colorado, California and Kentucky.
"Opportunities are wonderful. It was very humbling the last three or four weeks to go through that process and be involved in jobs. You learn a lot, but you also learn a lot about yourself and where you want to be," Andersen told the Idaho Statesman last week. "And you sit back and take a deep breath and know who you want to be able to be around. I love the kids I get to coach here. ... The kids I have in the program, it just was not time. I look them in the eye and I need to be where I'm at."
Wisconsin is headed to the Rose Bowl for a third straight season, and Alvarez is coaching the team. He was Wisconsin coach for 16 seasons before stepping down to focus on the job of athletic director, and handing the job to Bielema who was head coach in Madison for seven years.
Offensive coordinator Matt Wells could become a leading candidate to replace Andersen at Utah State.