CHICAGO — And so it was on Monday night Steve Kerr got the phone call from the Warriors that changed the future of the Knicks and Phil Jackson’s presidential reign.

The Warriors had a revision of their strategic planning regarding their head coaching vacancy and Kerr was now their No. 1 target.

Kerr was on the verge of agreeing to terms with the Knicks when the call arrived. Golden State owner Joe Lacob asked if he and his front-office mates could fly into Oklahoma City for a Tuesday meeting, igniting a whirlwind 48 hours that placed Kerr’s heart back in San Francisco and broke Jackson’s early Wednesday night.

Kerr was in Oklahoma City already, planning to cover Tuesday night’s Game 5 between the Thunder and Clippers for TNT, thinking the Warriors would probably hire Stan Van Gundy.

“I had been intrigued by that [Golden State] job for a while,’’ Kerr told The Post on Thursday. “But the timing wasn’t working at all. They were going to take time on the coaching search. I was pretty far down the road with the Knicks. But there was something in my gut that was holding me back from agreeing to terms.

“The Warriors called [Monday],’’ Kerr continued. “They had interviewed Stan and he was considering Detroit and they said they’d have to speed up the process. Was I interested in meeting? I had been nagged by a feeling that I wasn’t quite sure it was right going to New York.’’

Kerr first asked permission.

“I called Phil and told him this is what I wanted to do, that I planned to sit down with them,’’ Kerr said. “He gave me his blessing. He said ‘You have to feel this in your heart. Talk to them, see what they say and how you feel.’ ”

It was Jackson as a friend talking now. On Tuesday afternoon, Kerr took a cab out to the Oklahoma City airport, to a private terminal to meet with the Warriors for real this time. Lacob, a friend of Kerr’s for 20 years, was joined by Warriors general manager Bob Meyers, assistant GM Kirk Lacob and director of player personnel Travis Schlenk.

According to Kerr, they met for three hours. An offer of four years at $4.4 million per year was delivered — already one more year than the Knicks’ long-standing offer.

“I don’t know if it’s anything they said or if anything changed but something just clicked,’’ Kerr said. “Balancing family life with my career, it just seemed like such a better thing for my own welfare and family life. I think what attracted me to New York was Phil and the Knicks’ brand — a big-time franchise. But I hadn’t really wrapped my arms around it totally.’’

Kerr came out of the meeting buzzing, took a taxi cab back to downtown Oklahoma City to gear up for that night’s telecast with Marv Albert. Kerr informed Jackson, who matched the Warriors’ offer at four years, $17.6 million.

“My mind was racing,’’ Kerr said. “But I had a good feel for the OKC series, so the game calmed my mind. I called Phil and told him I wanted to sleep on it. I didn’t sleep a whole lot.

“I woke up [Wednesday] morning confident this was the right move for me.”

According to an NBA source, the Warriors on Wednesday added a fifth year, bringing the total base package to five years, $22 million. (The reported five years, $25 million is apparently only with various incentives added in).

“My agent [former Jets GM Mike Tannenbaum] did a great job getting that fifth year but it wasn’t a prerequisite,’’ Kerr said. “Both teams offered the same amount per year. It was competitive.”

Kerr flew Wednesday to his home in San Diego. One of his daughters plays volleyball at Cal-Berkley, the other attends the University of San Diego. His son will be a high school senior in the Del Mar, Calif., area next fall.

As one person close to Kerr said: “He’s very close to his kids. And unlike many of us, he also is very close to this wife.’’

Kerr got into this car Wednesday afternoon and pulled over to the side of the road to make “the phone call.”

“I dreaded telling Phil because he was fantastic through the process, so was Steve Mills, Jamie Matthews [the Knicks basketball operations VP],’’ Kerr said. “They made a fair contract offer. It was not an issue. It was the personal balance of family life.’’

As Tannenbaum told The Post on Thursday: “He had a lot of mixed feelings. He went back and forth, but he made a decision not based on economics.’’

Kerr wasn’t going to ask for a fifth year from the Knicks. He had his money and West Coast life back.

“Phil had just landed in Chicago and I told him my reasons and he couldn’t be any better about it,’’ Kerr said. “He told me if that’s how I felt, you’re making a good decision. That’s because Phil is Phil.’’