Stewart pulled out of Sunday's NASCAR race in Watkins Glen, N.Y., after his car struck and killed a 20-year-old driver, Kevin Ward Jr., while Ward was on foot during a sprint-car race Saturday night in upstate New York.
After contact with Stewart's car caused Ward's car to crash, Ward climbed from his car and was standing on the track and gesturing toward Stewart when Stewart's car hit him.
Stewart, who co-owns his NASCAR team Stewart-Haas Racing, "will have as much time as he needs to make that decision" about racing Sunday in Michigan, Stewart-Haas spokesman Mike Arning said in an email.
"It is still an emotional time for all involved, Tony included," Arning said. "He is grieving, and grief doesn't have a timetable."
NASCAR stock cars are 3,400-pound, full-bodied cars that bear a slight resemblance to everyday passenger cars. Sprint cars are light but powerful open-wheel cars -- some of which have large wings on top -- that often are raced on small dirt tracks.
Arning confirmed that Stewart, 43, had pulled out of a scheduled sprint-car race at Plymouth Speedway, a dirt track in Plymouth, Ind., scheduled for Saturday night and that Stewart wouldn't resume that type of racing "until further notice."
Ontario County Sheriff Philip Povero said no criminal charges were pending against Stewart but that an investigation of Ward's death was continuing.
Povero said Monday there were no current plans to talk to Stewart again and no timetable as to when his office's probe would be finished.
The sheriff renewed a request for spectators to turn over photos and videos of the crash. He said investigators were reconstructing the accident and looking at such factors as the quality of the lighting at the track and the fact that Ward was wearing a dark fire suit.
Another driver in the race, Cory Sparks, a friend of Ward's, told Associated Press he was a few yards back when Ward was struck.
"The timing was unsafe," Sparks said of Ward's decision to get out of his car to confront Stewart. "When your adrenaline is going and you're taken out of a race, your emotions flare."
Follow @PeltzLATimes for more motor racing news