The thing that brought Utopia back together ultimately wasn’t a burying of hatchets.

It was a surfeit of significant suitors.

Touring as a band is considerably more expensive and customarily less lucrative than touring as a solo act. So the encouragement, support, resources and deep pockets of a big-time promoter are, at the very least, enormously helpful.

Reached by phone, Todd Rundgren (Utopia’s founder and creative engine) said the band was courted by a number of major players and this helped convince him that a reunion was a good idea.

“We got a really positive response from several different promoters,” he said. “Ultimately, we went with Live Nation. It was their vote of confidence that was the real tripwire for the whole thing.”

Utopia performs at the Chicago Theatre on Tuesday night.

Rundgren has said for years that he wasn’t interested in the sort of half-ass reunion that would involve a couple of rehearsals and a couple of “greatest hits” concerts.

The current tour is the fruit of copious rehearsal time and fine-tuning.

One of the challenges of revisiting this era of Rundgren’s career was the bifurcated nature of the band.

Utopia started as a prog-rock outfit, but morphed into a more pop-friendly act.

Rundgren said revisiting the prog-rock era after all these years was daunting.

“That required the lion’s share of our rehearsal time,” he said. “Going back and trying to recapture everything that was represented in the first three albums of what we did.”

Rundgren said he initially formed Utopia as an opportunity to play guitar.

“The early records reflect that,” he said. “There’s much less singing overall and a lot more instrumentalizing.”

As his career progressed, Rundgren became “much less of a guitar player.”

“To have to go back and refocus on that messed with my brain a little,” he said. “To have to think like a guitar player.”

With all the hats he had to wear while putting this tour together, Rundgren said that the demands of the first few shows on him as a guitarist were a bit of a shock.

“Now I am starting to get back into the head of a guitar player,” he said. “I am thinking ahead instead of suddenly finding that ‘Oh, I am supposed to play this now?’ or “I am playing this now. What am I supposed to play next?'”

Rundgren said it was that way for everyone in the band.

As bassist and vocalist Kasim Sulton told Variety magazine in April: “I was just playing ‘Communion with the Sun’ earlier today and I’m like, ‘Oh man. Why did I play so many notes?'”

Each concert is structured to represent the transition that band went through, Rundgren said.

“The first set is more of the instrumental, prog-rocky stuff,” he said. “And the second set is more of the latter-day, songwriting-oriented pop stuff.”

Rundgren likens the first set to playing in a blizzard.

“Everything is coming at you so fast,” he said. “The second set seems a breeze by comparison. I kept thinking, ‘Maybe we should just do the history of the band backwards. Start at the end and work our way back to the beginning.'”

The band’s transition mirrored Rundgren’s transition into one of the more notable pop songwriters and producers of the 20th century.

Practicality and pragmatism are what drove the band’s transition.

“We weren’t getting a lot of records on the radio,” Rundgren said. “We were always more of an album act. As long as there was album radio, we got some airplay. But as time went on, (the Bearsville record label) lost interest in the band.

“We weren’t getting the tour support which made those big shows possible,” he said. “As we got more dependent on ourselves, we started to think more economically: ‘Let’s not write these big, top-heavy songs that require pyramids.'”

Nevertheless, Rundgren said the band never lost its “conceptual flair.”

While preparing for this tour, the band suffered a seemingly catastrophic setback.

With a month to go before the opening date, keyboardist Ralph Schuckett decided he wasn’t healthy enough for the rigors of the road.

Rundgren said he found a message about Schuckett on his phone after flying from Austin to Hawaii (his home is on the island of Kauai).

Given Rundgren’s perfectionism, perhaps readers can imagine how this news struck him.

“At that point, I wanted to walk into the ocean and just keep going,” he said, laughing. “Not look back.”

A Utopia keyboardist has to be as strong a singer as he is a player, so it isn’t surprising to learn that the search for a replacement went nowhere initially.

“After sulking for a while, I decided we couldn’t just go out and hire the usual stand-in,” he said. “There was somebody out there. We just didn’t know who it was.”

As part of an expanded, all-points-bulletin search, Rundgren sent a message to his son, ReBop.

“I asked him, ‘Who is the best keyboard player you know?’ He is zeroed in on a different generation. I knew our shout-out was only likely to yield a lot of dirty, old guys.”

ReBop came back with a name: Israeli-born keyboardist Gil Assayas.

“What Gil had that nobody else did was copious representation on YouTube,” Rundgren said. “In other words, we could evaluate how he played in all sorts of contexts. There was an interview, so we could get some idea about his personality.”

Assayas turned out to be the ideal choice, he said.

“We sent him this stuff and within a week he was already playing as much as two keyboard players had been playing before,” Rundgren said.

Assayas was even able to recreate all the sounds from the analog era on his modern set-up.

“I was kind of stunned us how quickly he absorbed it,” Rundgren said. “Suddenly, it was a sigh of relief.”

Rundgren said it is too early to tell if this reunion will continue beyond this tour.

“There are those elements that always made it hard to get it organized,” he said. “Roger and Ralph had retired from the road. They had other things to do. They actually had employers. So the question always was, ‘How are they going to find a three-month window?’

“Those issues linger,” Rundgren said. “We have to wait until the end and look back to see what we accomplished. We have to see if it was worth the effort of doing it. If so, we’ll probably start talking about doing it again.”