INDIANAPOLIS -- Tony Stewart has thought about competing in the 2019 Indianapolis 500, but he isn't planning on making a start next May at Indianapolis Motor Speedway.

He also isn't giving up on his thoughts about returning to the Indianapolis 500 at some point.

When discussing his future racing plans, Stewart said Aug. 9 that he was interested. "Everything is a possibility," he said. "There's nothing that I've written off and said, 'You know what, I'm never doing it.' ... [Indy 500] is not out of the question."

In an interview Sunday during the Brickyard 400 telecast on NBCSN, the former NASCAR and Indy Racing League champion said he won't do it in 2019. Stewart, who retired from NASCAR competition after the 2016 season, has not competed in the Indianapolis 500 since 2001, and a win in that race would be the biggest of his career.

Tony Stewart, shown here attending a practice for the Indianapolis 500 in May, has said he's interested in running the race again, but said on Sunday that it won't happen in 2019. AP Photo/Michael Conroy

"Not this coming year," he said about a potential Indianapolis 500 start. "I did what I normally do -- I let my mouth open before I actually thought about what I was saying and mentioned I was open to the possibility again.

"I realistically am. I have talked to Michael Andretti. Roger Penske still says I have an open invitation. I think (Chip) Ganassi would put me back in a car. But a call I didn't expect and an email I didn't expect was from Bobby Rahal and David Letterman to run one of their cars."

Stewart, who would be 49 years old by the time of the 2020 Indianapolis 500, said he had not responded to Rahal. He would need the time to prepare (and lose 20 pounds), and the IndyCar Series finishes its season next week on the Sonoma Raceway road course.

"I would want to run an oval race sometime this coming year to get ready maybe for 2020 if I'm going to do it," Stewart said during the NBCSN interview. "I've learned to never say never. But I keep doing the math and I'm like, 'I'm pretty sure 49 is probably not a real good age to resurrect an IndyCar career.

"But who knows? I've done a lot dumber things than that."