The offer that Sirius XM Satellite Radio was too good to pass up.

That’s what Chris “Mad Dog” Russo told John Graney on the latter’s Sunday night sports talkshow on WGDJ-AM (1300).

Russo ended a nearly 19-year relationship with WFAN-AM (660) Aug. 14 when he split from Mike Francesa and the “Mike and the Mad Dog” show for a job at Sirius XM. Russo’s show will headline “Mad Dog Radio,” a reformatted channel that will cover the spectrum of sports with engaging talk, high profile interviews, up-to-the-moment news and live remote broadcasts from the biggest sporting events.

Russo’s first show will be Sept. 15, although he will make three appearances on Sirius XM prior to that.

“It was a chance I had to take,” Russo said. “I know it’s a tough decision leaving a great station and a partner I worked with for 19 years at a big-time show. I just felt that if I was ever going to leave, this was the opportunity I was going to have to take.”

Russo said most of the shows on “Mad Dog Radio” will be based in New York. But he did say he wants to hire a West Coast host for the overnight shift.

Russo gave some insight into how things were handled with WFAN over the final two months. He said he had nine months remaining on his contract with the station.

“The station and my agent got together on a conversation on June 19,” Russo said. “There were no formal proposals on the 19th from ’FAN, and I don’t think my agent made it seem like I could leave. I told the station on July 10 that I would let you know before you sit there and start a silly negotiation process that you might be banging your head against the wall. I did not want ’FAN to go through a charade just to make me an offer [and] say I got an offer.”

Graney asked Russo about how Francesa will do solo. It sounded like Russo was choosing his words carefully.

“I think Mike is looking forward to the challenge,” Russo said. “Mike loves New York. He loves living there. . . . I think he will enjoy having the real estate of [having] 1-6:30 [p.m.] all by himself. I think the change will do him good. I don’t want to say [he’s] happy. Mike will have some adjustments to make, as will I.

“I think overall, Mike’s going to be motivated. The challenge is going to get him into it.”