The earliest a state job in Wisconsin can be filled is two weeks after the job's posting, meaning Andersen can't be officially announced by the school until Thursday.
The school was expected to introduce Andersen at a news conference on Thursday, but a snowstorm might change those plans.
Andersen interviewed with Wisconsin on Monday.
The Wisconsin State Journal reported Tuesday that two sources close to the Badgers program said Andersen was athletic director Barry Alvarez's top choice to succeed Bret Bielema, who left to take the Arkansas job.
Alvarez certainly is familiar with Andersen. On Sept. 15, the Aggies nearly upset the Badgers, but lost 16-14 when kicker Josh Thompson missed a 37-yard field goal in the final seconds.
In four years at Utah State, Andersen was 27-24, including this season's 11-2 mark. The Aggies nearly went unbeaten, losing only to Wisconsin and BYU, 6-3.
Andersen led Utah State to its first bowl victory in 19 seasons on Saturday, a 41-15 triumph over Toledo in the Famous Idaho Potato Bowl.
It's been a remarkable rise for a program that had been near the bottom of major college football for years, and stuck in distant third in its own state behind BYU and Utah. The Aggies won nine games in the previous four seasons before Andersen took over. The last football coach to finish his tenure in Logan, Utah, with a winning record was Phil Krueger who went 21-12 from 1973-75.
Prior to Utah State, Andersen was an assistant at Utah from 2004-08 (defensive coordinator from 2005-08), head coach at Southern Utah in 2003 and an assistant at Utah from 1997-2002.
Besides Andersen, others linked to the Wisconsin opening included Miami's Al Golden, Oregon State's Mike Riley, then-Western Kentucky coach Willie Taggart, Wisconsin defensive coordinator Chris Ash and Jacksonville Jaguars assistant Mel Tucker.
Andersen drew interest from California, Colorado and Kentucky last month, but decided to pass on those opportunities and received a contract extension from Utah State.
"The interest I have received is a compliment to the quality young men in this program," Andersen said in the statement released Nov. 30. "I love Cache Valley, this university and these young men, and I am humbled and excited to continue to be the coach here. The leadership of President (Stan) Albrecht and Mr. Barnes, as well as the support from the fans and community, are big reasons why this is the right place for myself and my family at this time."
That was before Wisconsin had an opening. Bielema announced he was leaving on Dec. 4, three days after the Badgers won their third straight Big Ten title and trip to the Rose Bowl Game presented by Vizio.
As late as last week Andersen was saying he was committed to the Aggies.
"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," he told the Idaho Statesman newspaper.
When Wisconsin called, Andersen changed his mind.
It's a tough spot in which many coaches find themselves. It's imperative for recruiting purposes to show unwavering commitment to your current school. But when a coach does jump to another job, he looks like a liar.
"If you can, it's good to not say anything," former Arkansas and Mississippi coach Houston Nutt said. "It's almost now impossible because there's so much information out there."
Washington State coach Mike Leach said he felt his only obligation was to his employer and his team.
"I think you handle it honestly with the people you work for, but by the same token you don't let the media or public into your personal business," he said.
Apparently, many in Utah were caught off guard by the Andersen-to-Wisconsin news.
"I can't believe this..." Utah State receiver Alex Wheat posted on his Twitter account when word started to spread.
"I hate rumors.." tight end DJ Tialavea tweeted.
A few hours later, that changed.
"Coach A just called me. Explained the situation. No hard feelings. I have nothing but respect for the man. We must fight on. #AggieNation," Wheat posted.
The Wisconsin State Journal reported Wednesday that Andersen spent Tuesday night calling his Utah State players.
"Just got that phone call always have and always will love ya coach!" Tialavea tweeted.
ESPN.com's Adam Rittenberg contributed to this report. Brett McMurphy covers college sports for ESPN.